If you can work with sub-resources, you can delete a sub-resource if it has no history of status updates. In addition, you cannot delete a sub-resource that is the primary one of its type. To delete the sub-resource, make another one the primary first.
To delete a sub-resource
Point to Setup and in the menu, click Resources. The Resource List opens.
Locate the resource and on that row, click Sub-Resources. The Sub-Resource List page opens.
Locate the sub-resource and, on that row, click Delete. A confirmation message appears.
