How To Destroy App Activities -:
1) Firstly Go To Settings>> about Phone >> Then Tap On "Build Number" 5-8 Times
2) Now You Will See a Popup That" Devoulper Option Enabled Now "
3) Go Back And Click On Devoulper Option
4) Slide Down And Click On "Don't Keep Activities"
5) If You Don't Want to Destroy all activities then Select "Background Process Limit"
6) That It! Problem Solved