I need to remove one of the iCloud accounts of my account
How do I remove one of the iCloud account
iPad Air 3 Wi-Fi
The iCloud email address or a separate Apple ID used for iCloud?
You can't remove/change @iCloud.com, @me.com or @mac.com aliases.
iCloud - Create or change email aliases.
If a separate Apple ID, use the below as a guide of where to sign out.
What to do after you change your Apple ID or password - Apple Support.