removed unused method

src/app/pages/algorithms/four-color/four-color.component.html

@@ -57,11 +57,8 @@
       <canvas #fourColorCanvas
               (mousedown)="onMouseDown($event)"
               (mousemove)="onMouseMove($event)"
-              (mouseup)="onMouseUp()"
-              (mouseleave)="onMouseUp()"
               (touchstart)="onTouchStart($event)"
               (touchmove)="onTouchMove($event)"
-              (touchend)="onMouseUp()"
       ></canvas>
     </div>
   </mat-card-content>

src/app/pages/algorithms/four-color/four-color.component.ts

@@ -243,8 +243,6 @@ export class FourColorComponent implements AfterViewInit {
     this.getGridPos(event);
   }
 
-  onMouseUp(): void {}
-
   onTouchStart(event: TouchEvent): void {
     event.preventDefault();
     const touch = event.touches[0];