Restrictions passcode
How can I get my restrictions passcode back
These are the minimum requirements to reset the ScreenTime passcode:
- The device must run iOS/iPadOS 13.4 or later;
AND
- You must know the Apple ID & Password that were used to set up that ScreenTime Passcode.
If you meet both above requirements, these are the instructions:--> If you forgot your Screen Time passcode – Apple Support
But since your iPhone 6 cannot be updated beyond iOS 12.5.4 version because of hardware (CPU/RAM) incompatibility, you need to erase that device following these instructions (even if related to the passcode to lock/unlock device's screen):--> If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support
The bad news is that you cannot restore data from a backup, since the ScreenTime passcode would come back in.
Regards
Giulio