Method 1:
Long press the app icon and click on the App Info
a. Click Force Stop to end the process of running the application.
b. Click Battery Usage to turn off Allow background activity and Allow auto launch, Allow this app to launch other apps.
Method 2:
realme UI 1.0 & above versions: Settings > Additional / System settings > Process manager > Click Deep cleanup.
realme UI S & T & R & Go & U Edition: Not supported