I can't remember the restriction code for 6s to erase the data before turning it in.

I need to delete the personal data prior to returning to the vendor however I can not remember the restriction code which is different than the passcode I used. I set the phone up 2 years ago and have NO idea what that 4 digit number is. Are there any work arounds for this?

Welcome to iMore! All you need do is go to iCloud in settlngs. Toggle off "Find My iPhone".
You might also toggle off iMessage.
That's it. Then go to settings > General > Reset> Erase all content and settings.
That's all.