Restrictions passcode

You can't remove it without removing the data. From the article below.

If you can't remember a restrictions passcode that you created on a previous version of iOS, or you forgot your Screen Time passcode, you need to erase your device, then set it up as new to remove the passcode. Restoring your device won't remove your old passcode.

Parental controls

You will need to restore the device to factory settings. Do not restore from a backup made when the Screen Time code was active.

Restore to Factory setting

I did that with my son so you have to call Apple they'll give you all the steps you won't Loose all your data you just have to do the steps that apple told you