you canarchivethe teamspace, but still need to be the owner. This removes the teamspace from your sidebar but does not delete it entirely. Archiving a teamspace requires that remove its members, butdoes not delete its content. You can refer to an archived teamspace...
While you do have the ability to delete a workspace in Notion, a teamspace works a bit differently. As of this writing, you can’t delete a teamspace, but you can archive it. This removes the teamspace and all of its pages from your sidebar. You must be the teamspace owner to archive...