I can’t remember my restrictions passcode

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.

The above response is based on an assumption that you are using iOS version 12.x.x.

Axel F.

If the iOS version is so old that Screen Time does not yet exist, when a Restrictions passcode is forgotten, the iPhone must be erased and set up as new.

How to erase your iPhone, iPad, or iPod touch - Apple Support

If you forgot your Screen Time passcode - Apple Support