How can you log off an icloud account if you don't have password

You need to sign out; there isn't a way to bypass activation lock without the password (or assistance from Apple if you are the original owner of the device). Turn off Find My iPhone Activation Lock - Apple Support

You can get help with the password: If you forgot your Apple ID password - Apple Support

hi35 Said:

”how can you remove an icloud login if you don't know the password?”

Is this your device that you purchased new from Apple? Or is it a used device that you obtained from someone?

On a Mac, do so in iTunes. On a different device, it would be performed in Settings.

If it is used, then the person already signed into iCloud on the device would have to sign themselves out of it, disassociate it from their account, and then transfer ownership of it to you.