I forgot my restrictions password on my iphone x

Also see this support document for an explanation of Parental Controls, Restrictions on the iOS devices. How to use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support You cannot restore a backup, as the passcode is in the backup. You will have to restore to factory and set it up as new.

You will need to restore your device as new to remove it.

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