Como puedo hacer para borrar otras cuentas

Do you really want to delete your iCloud Apple ID(s) ? Or just remove then from your devices?

Only Apple can delete an AppleID for you - deleting the AppleID will cause you to lose your purchases and subscriptions, all purchases are tied to your AppleID. Your AppleID is your lifetime passport in the Apple universe.

See: Manage and use your Apple ID - Apple Support

Account Management: If you See a Could Not Create Apple ID or Could Not Set Up iCloud Message - Apple Support