Removing apple id with no password

You cannot obviously. If you could, what would even be the point of using passwords?

You can always erase the device by restoring it as a new device with iTunes and a computer. But the AppleID cannot be removed from the device without the password. Merely erasing it will not remove Activation Lock.

If you forgot the Apple ID password, enter the Apple (iCloud) ID, and click Forgot Password. See if you can get an email option if necessary.

Apple ID - Manage            

Apple ID – Forgot Password