diff --git a/src/app/group/components/group-edit/group-edit.component.html b/src/app/group/components/group-edit/group-edit.component.html
index 591e0ef..f4d8433 100644
--- a/src/app/group/components/group-edit/group-edit.component.html
+++ b/src/app/group/components/group-edit/group-edit.component.html
@@ -23,7 +23,8 @@
       <h3>Users:</h3>
       <app-group-users 
       [groupUsers]="group.users"
-      [adminId]="group.admin.id"></app-group-users>
+      [adminId]="group.admin.id"
+      (deleteUser)="onDeleteUser($event)"></app-group-users>
     </div>
     <div *ngIf="group.admin.id === currentUserId && group.groupCandidates" class="mb-5 border p-3">
       <h3>Group candidates:</h3>
diff --git a/src/app/group/components/group-edit/group-edit.component.ts b/src/app/group/components/group-edit/group-edit.component.ts
index fed1cbd..e14e518 100644
--- a/src/app/group/components/group-edit/group-edit.component.ts
+++ b/src/app/group/components/group-edit/group-edit.component.ts
@@ -37,7 +37,7 @@ export class GroupEditComponent implements OnInit {
   }
 
   onLeaveGroup(): void {
-    this.groupService.leaveGroup(this.groupId).subscribe(() => {
+    this.groupService.leaveGroup(this.groupId, localStorage.getItem('userId')).subscribe(() => {
       this.router.navigateByUrl('/group');
     });
   }
@@ -55,4 +55,10 @@ export class GroupEditComponent implements OnInit {
     });
   }
 
+  onDeleteUser(userId: string) {
+    this.groupService.leaveGroup(this.groupId, userId).subscribe(() => {
+      this.group$ = this.groupService.getGroup(this.groupId);
+    });
+  }
+
 }
diff --git a/src/app/group/services/group.service.ts b/src/app/group/services/group.service.ts
index 2dd2d29..a0f9435 100644
--- a/src/app/group/services/group.service.ts
+++ b/src/app/group/services/group.service.ts
@@ -28,8 +28,8 @@ export class GroupService {
     return this.http.get<Group[]>(`${environment.host}${environment.apiEndpoints.groups.getCurrentUserGroups}/${localStorage.getItem('userId')}`);
   }
 
-  leaveGroup(groupId: number): Observable<void> {
-    return this.http.get<void>(`${environment.host}${environment.apiEndpoints.groups.leave}/${groupId}/${localStorage.getItem('userId')}`);
+  leaveGroup(groupId: number, userId: string): Observable<void> {
+    return this.http.get<void>(`${environment.host}${environment.apiEndpoints.groups.leave}/${groupId}/${userId}`);
   }
 
   delete(groupId: number): Observable<void> {
diff --git a/src/app/subject/components/subject-edit/subject-edit.component.html b/src/app/subject/components/subject-edit/subject-edit.component.html
index cb72912..2db178a 100644
--- a/src/app/subject/components/subject-edit/subject-edit.component.html
+++ b/src/app/subject/components/subject-edit/subject-edit.component.html
@@ -42,7 +42,7 @@
       </div>
     </div>
     <div class="">
-      <button (click)="onAddNewTest()" class="btn btn-primary">Add new test</button>
+      <button [disabled]="!editable" (click)="onAddNewTest()" class="btn btn-primary">Add new test</button>
     </div>
     <div *ngFor="let assignment of subjectForm.get('assignments')['controls']; let i = index" class="list-group list-group-flush">
       <div class="list-group-item">
@@ -68,7 +68,7 @@
       </div>
     </div>
     <div class="">
-      <button (click)="onAddNewAssignment()" class="btn btn-primary">Add new assignment</button>
+      <button [disabled]="!editable" (click)="onAddNewAssignment()" class="btn btn-primary">Add new assignment</button>
     </div>
     <div *ngFor="let comment of subjectForm.get('comments')['controls']; let i = index" class="list-group list-group-flush">
         <div class="list-group-item">
@@ -82,10 +82,10 @@
         </div>
     </div>
     <div class="">
-        <button (click)="onAddNewComment()" class="btn btn-primary">Add new comment</button>
+        <button [disabled]="!editable" (click)="onAddNewComment()" class="btn btn-primary">Add new comment</button>
     </div>
     <div class="mt-4">
-        <button (click)="onSubjectSave()" class="btn btn-primary">Save</button>
+        <button [disabled]="!editable" (click)="onSubjectSave()" class="btn btn-primary">Save</button>
     </div>
   </form>
 </div>
diff --git a/src/app/subject/components/subject-edit/subject-edit.component.ts b/src/app/subject/components/subject-edit/subject-edit.component.ts
index 0995266..5a026ed 100644
--- a/src/app/subject/components/subject-edit/subject-edit.component.ts
+++ b/src/app/subject/components/subject-edit/subject-edit.component.ts
@@ -1,3 +1,4 @@
+import { GroupService } from './../../../group/services/group.service';
 import { Assignment } from './../../interfaces/assignment.interface';
 import { Component, OnInit } from '@angular/core';
 import { FormGroup, FormControl, Validators, FormArray } from '@angular/forms';
@@ -18,9 +19,11 @@ export class SubjectEditComponent implements OnInit {
   subjectForm: FormGroup;
   subjectId: number;
   groupId: number;
+  editable: boolean;
 
   constructor(private activatedRoute: ActivatedRoute,
               private subjectService: SubjectService,
+              private groupService: GroupService,
               private router: Router) { }
 
   ngOnInit(): void {
@@ -29,9 +32,13 @@ export class SubjectEditComponent implements OnInit {
     this.subjectForm = this.createSubjectForm();
     this.subjectId = this.activatedRoute.snapshot.params.id;
     if (this.subjectId) {
-      this.subjectService.getById(this.subjectId).subscribe((subjectPayload) => {
+      this.subjectService.getById(this.subjectId, localStorage.getItem('userId')).subscribe((subjectPayload) => {
         this.subject = subjectPayload;
         this.updateSubjectForm(this.subject);
+        this.editable = this.subject.editedBy === localStorage.getItem('userId');
+        if (!this.editable) {
+          this.subjectForm.disable();
+        }
       });
     }
   }
@@ -45,6 +52,7 @@ export class SubjectEditComponent implements OnInit {
       labTeacher: '',
       mainExam: false,
       examDate: new Date(),
+      editedBy: null,
       tests: [],
       assignments: [],
       comments: []
@@ -60,6 +68,7 @@ export class SubjectEditComponent implements OnInit {
       labTeacher: new FormControl(''),
       mainExam: new FormControl(false),
       examDate: new FormControl(this.parseDateTimeToISOFormat(new Date())),
+      editedBy: new FormControl(null),
       tests: new FormArray([]),
       assignments: new FormArray([]),
       comments: new FormArray([]),
diff --git a/src/app/subject/components/subject-list/subject-list.component.html b/src/app/subject/components/subject-list/subject-list.component.html
index 1bd4d5b..1111e22 100644
--- a/src/app/subject/components/subject-list/subject-list.component.html
+++ b/src/app/subject/components/subject-list/subject-list.component.html
@@ -23,6 +23,7 @@
       </div>
       <div class="subject-buttons d-flex align-items-center">
         <button (click)="onEdit(subject.id)" class="btn btn-primary">Edit</button>
+        <button *ngIf="adminId === userId && subject.editedBy != null" (click)="onUnlock(subject.id)" class="btn btn-primary ml-2">Unlock</button>
         <button *ngIf="adminId === userId" (click)="onDelete(subject.id)" class="btn btn-primary ml-2">Delete</button>
         <button *ngIf="adminId !== userId" (click)="onDeleteRequest(subject.id)" class="btn btn-primary ml-2">Delete request</button>
       </div>
diff --git a/src/app/subject/components/subject-list/subject-list.component.ts b/src/app/subject/components/subject-list/subject-list.component.ts
index 136787d..d4b078f 100644
--- a/src/app/subject/components/subject-list/subject-list.component.ts
+++ b/src/app/subject/components/subject-list/subject-list.component.ts
@@ -15,6 +15,7 @@ export class ListComponent implements OnInit {
   @Output() deleteSubject = new EventEmitter<number>();
   @Output() addNewSubject = new EventEmitter<void>();
   @Output() editSubject = new EventEmitter<number>();
+  @Output() unlockSubject = new EventEmitter<number>();
   displayedColumns: string[];
 
   constructor() { }
@@ -39,4 +40,8 @@ export class ListComponent implements OnInit {
     this.editSubject.emit(id);
   }
 
+  onUnlock(id: number): void {
+    this.unlockSubject.emit(id);
+  }
+
 }
diff --git a/src/app/subject/components/subject-main/subject-main.component.ts b/src/app/subject/components/subject-main/subject-main.component.ts
index 931ffe5..46386ff 100644
--- a/src/app/subject/components/subject-main/subject-main.component.ts
+++ b/src/app/subject/components/subject-main/subject-main.component.ts
@@ -63,7 +63,13 @@ export class SubjectMainComponent implements OnInit {
   }
 
   onEditSubject(id: number): void {
-    this.router.navigateByUrl(`subject/edit/${id}/${this.groupId}`);
+    this.router.navigateByUrl(`subject/edit/${id}/${this.userId}`);
+  }
+
+  onUnlockSubject(id: number): void {
+    this.subjectService.unlock(id).subscribe(() => {
+      this.subjects$ = this.subjectService.getListByGroupId(this.groupId);
+    });
   }
 
 }
diff --git a/src/app/subject/interfaces/subject.interface.ts b/src/app/subject/interfaces/subject.interface.ts
index 189adca..dfb34d2 100644
--- a/src/app/subject/interfaces/subject.interface.ts
+++ b/src/app/subject/interfaces/subject.interface.ts
@@ -10,6 +10,7 @@ export interface Subject {
   labTeacher: string;
   mainExam: boolean;
   examDate: Date;
+  editedBy?: string;
   tests: Test[];
   assignments: Assignment[];
   comments: Comment[];
diff --git a/src/app/subject/services/subject.service.ts b/src/app/subject/services/subject.service.ts
index aaee05b..510d1b4 100644
--- a/src/app/subject/services/subject.service.ts
+++ b/src/app/subject/services/subject.service.ts
@@ -19,8 +19,8 @@ export class SubjectService {
     return this.http.delete<void>(`${environment.host + environment.apiEndpoints.subjects.delete}/${id}`);
   }
 
-  getById(id: number): Observable<Subject> {
-    return this.http.get<Subject>(`${environment.host + environment.apiEndpoints.subjects.getById}/${id}`);
+  getById(id: number, userId: string): Observable<Subject> {
+    return this.http.get<Subject>(`${environment.host + environment.apiEndpoints.subjects.getById}/${id}/${userId}`);
   }
 
   getListByGroupId(groupId: number): Observable<Subject[]> {
@@ -30,4 +30,8 @@ export class SubjectService {
   update(subject: Subject): Observable<void> {
     return this.http.put<void>(`${environment.host + environment.apiEndpoints.subjects.update}/${subject.id}`, subject);
   }
+
+  unlock(id: number): Observable<void> {
+    return this.http.get<void>(`${environment.host + environment.apiEndpoints.subjects.unlock}/${id}`);
+  }
 }
diff --git a/src/environments/environment.ts b/src/environments/environment.ts
index e071207..35258fb 100644
--- a/src/environments/environment.ts
+++ b/src/environments/environment.ts
@@ -7,7 +7,8 @@ export const environment = {
       getById: 'api/subjects/get-by-id',
       delete: 'api/subjects/delete',
       add: 'api/subjects/add',
-      update: 'api/subjects/update'
+      update: 'api/subjects/update',
+      unlock: 'api/subjects/unlock'
     },
     deleteRequests: {
       getListByGroupId: 'api/subjectDeleteRequests/list-by-group-id',