You can delete a template by removing it from the inventory or deleting the template from the disk. If you remove the template from the inventory, it remains on the disk and can be reregistered with vCenter Server to restore it to the inventory.

If you remove a template from the inventory, it is unregistered from the vCenter Server inventory, but it is not removed from the datastore.

Deleted templates are permanently removed from the system.

Templates can become unregistered from the vCenter Server if they are removed from the inventory or if the hosts with which they are associated are removed from the vCenter Server and then readded.