I did what the best solution above says but the problem is "please sign in using one of the account's user" always pops out.Bu

[keideurama.ch]

Synced Google Account in my phone

 

[Saga Lout]

It's Google's way of telling you it isn't your phone. Have you just acquired it? If so, ask the original owner to set up an account for you then delete their own account - not just removing it from that device but deleting it completely.

Chances are they won't want to do that and might agree to buy it back from you.