How do you remove an old Apple ID from my phone sold to someone

old Apple ID from my phone sold to someone

From what you say, you sold a phone to somebody and now need to remove your information Read this article --> What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

Some of the things you can do remotely.

If you instead mean you have a phone somebody sold to you:

'Activation Lock for iPhone, iPad, and iPod touch' is a security feature that's designed to prevent anyone else from using an iPhone, iPad, or iPod touch, if it's ever lost or stolen. To learn more click here --> http://support.apple.com/HT201365

For an individual to remove an activation lock absolutely requires the information for the account that applied the lock. Click on this link to learn 'How to remove Activation Lock' --> https://support.apple.com/HT201441

If you do not know the required information and you are not the original owner, get the owner of the account to remove the lock or return the device for a refund or recycle it. The device is otherwise useless to you. If the owner is unknown and has not provided contact information as a message showing in the login screen, there is no way to contact the owner unless the person who gave you the device knows them.

You can’t remove the Apple ID. Unless you have other persons username and password. You will have to speak with them or get the bill of sales from that person.