reset restriction passcode
how to reset iPad if a restriction is forgotten
It would have been easier to answer your question if you had listed the model of your iPad and the iOS/iPadOS that is running.
If you can't remember a restrictions passcode that you set on a previous version of iOS, or you forgot your Screen Time passcode, then you need to erase your device, then set it up as a new device to ➔ How to remove the passcode. Restoring your device from a backup won't remove your passcode UNLESS your backup was created BEFORE the screen time passcode was created.
If you have updated to iOS 13/14 then follow these instructions ➔ If you forgot your Screen Time passcode - Apple Support
Axel F.