I forgot my restriction passcode

Try restoring to a backup that you took before you set the code, or reset the phone back to factory defaults (you may need to use recovery mode to reset the phone : If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support) - for both, first copy off anything that you want to keep

To remove restrictions, you will have to restore your device.

This article will help you with that: HT204184

If you restore from an iTunes or iCloud backup, restrictions will return. You must setup as new to remove restrictions. I suggest going into iCloud on the device, and backing up items individually (photos, contacts, notes, etc.) for minimal data loss.

If you do not have enough iCloud storage, you can upgrade to a $0.99 a month plan, for 50GB. If you need to upgrade: Buy more iCloud storage - Apple Support