Types can be deleted by clicking Types on the sidebar from the Home tab, and clicking the delete icon next to the type we want to delete.
If we have a value (object or list) of a particular type in a tenant, then we can not delete that type without first deleting the value. If we try to do so, we get a system alert: Element cannot be deleted due to dependencies.
A word of caution! Deleting a type deletes it permanently from the entire tenant.