I have this old iphone 4s. Well I restarted everything but it connected to an old icloud that I can't remember. What do I do?

I have this old iphone 4s. Well I restarted everything but it connected to an old icloud that I can't remember. What do I do?

If you can't recall the security credentials then you use the tools Apple provide for legitimate account owners to recover those details.

If you no longer have access to the account recovery options you originally set up then you simply can't access the account. As you forgot you had the account anyway there's no great loss in abandoning it and starting a new one.