Screen time password recover

Something you can try.

 To change or turn off the passcode on your child's device, tap Settings > Screen Time > [your child's name]. Then tap Change Screen Time Passcode or Turn Off Screen Time Passcode, and authenticate the change with Face ID, Touch ID, or your device passcode.

Parental controls

Try restoring to a backup you took before you set the code, or just do : erase your device, then set it up as a new device