You will only be able to reset a forgotten ScreenTime Passcode if, when the Password was set, you associated an AppleID for recovery. You should note that setting a recovery AppleID is an entirely optional step - and can be skipped.
If you have forgotten the ScreenTime passcode, one of the two procedures outlined within this link should resolve the problem:
If you forgot your Screen Time passcode - Apple Support
If you have an older iPad capable of supporting iPadOS 13.x or later, you should update to the most recent supported version before attempting to resolve a forgotten ScreenTime passcode. The most recent iPadOS updates have introduced the mechanism whereby a forgotten ScreenTime passcode can be reset without wiping the iPad - using the recovery AppleID is previously set.
To reset a forgotten ScreenTime passcode on older versions of iOS/iPadOS, the iPad must be reset “as new”, losing all locally stored data. In this situation, you’ll not be able to restore your data from an iCloud or iTunes backup - as the forgotten passcode is integral to the backup.