How can i fix this problem

[AC Question]

I bought a new phone and I used my friend's Google account, after my phone was reset he told me he forgot all the details

 

[Golfdriver97]

Welcome to the forums. Your friend would have to change his google password. After that I think it takes up to 72 hours before you can attempt to put in his google account.

 

[hallux]

There's a 24 hour waiting period after a password reset to use that account to sign in to a phone.

For the OP - I'd suggest that once that's done that you properly remove his account and create your own to use with the phone, then you don't have to worry about this kind of thing.

Factory Reset Protection: what you need to know | Android Central