screen time password

Unfortunately, you have only two choices:

Cohabit with the restrictions you (or someone else) set, or

Restore your iphone to factory settings and, in the end set it up as new, following these instructions:

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

Do not try to restore data from a previous backup (unless it was created before you set that passcode), 'cause that passcode will be added again.

Regards

Giulio

Erase your iPhone and set it up as new.