iphone 10 is locked

Hello ~ That is the activation lock. If the person/persons that you bought the iPhone from cannot or will not remove it …the iPhone is basically useless to you. If they cannot/will not remove it…return it and get your money back. We cannot help remove it nor can Apple. Take a look here:

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Also:

The All Too Common SAD Reality of Buying a Used iPad/iPhone

~Katana-San~

Return the phone for a refund immediately, or turn it in to the police, since it has likely been reported as stolen.

The phone is completely worthless until the owner removes the lock on the phone. In case you haven't figure out yet.....the person you bought the phone from was not really the owner.