how to delete an iCloud account without the password on Mac

I have two iCloud accounts on my laptop, but the dominant one i don't use nor do i know the password for. I cannot sign out without the password. When i click on "forgot password" it takes me to Manage your Apple ID. My Apple ID is synced with my other iCloud account so this is no help. How do i get rid of it? I also am unable to sync my iMessages on my iPhone with my messages on my laptop.

Any help is appreciated!

Thanks