For some reason, this parameter "Rough Width" in the family cannot be deleted. I have seen this in the past and one of the reasons has to do with the family has been upgraded year after year.
Question is "How do we get rid of this parameter?"
First, add a new reference plane on the side like the image.
Then, select the parameter and choose "Edit Witness Lines" from the option.
Have the dimension string snapped to the new reference plane, then select the reference to remove from the original location.
Once this is done, go ahead and delete the ref. plane. Without the ref. plane, the dimension string will be deleted.
This little trick can work on pre-existing parameter from the family template such as casework, baluster and window (wall hosted) family.