trying to reset Iphone 8 to trade in for new, I have apple ID and password and code there is a secondary 4 digit code I can't remember how do I reset.

I'm trying to reset and erase iphone 8 to trade in to AT&T to upgrade to Iphone 13pro, I have Apple ID and Password, 4 digit code to unlock phone, I hade set up a secondary 4 digit code for parental control that I can't remember, so i select reset punch in 4 digit code then it asks me for the 2nd 4 digit code which i can't remember and after few attempts it asks me to try later. Any way to connect to the computer to erase.