Reply To: Replace A PIN
The best thing to do in this instance is to uninstall the app, and try reinstalling it. Want to see if that works?
If the pin persists, mind trying these steps:
Select the app to uninstall
Press Force Stop
Press Clear Cache
Press Clear Data
Use uninstaller app – Easy Uninstaller to remove CleanBrowsing (ref: https://play.google.com/store/apps/details?id=mobi.infolife.uninstaller)