Hi @NNAhmedFHQZQ, you need to use Purge Unused command under the Manage tab and find the label type you need to remove. I'd recommend unselect all items then only select what you need to delete.
Please check the link below as the solution provided previously.
https://forums.autodesk.com/t5/revit-architecture-forum/can-t-delete-label-type-in-annotation-family...
Please let me know if your issue resolved and have this accepted as a solution and give kudos!
Şafak Binici
BIM Expert
