Go to the view properties and where the number is delete the entry and the running numbers will disappear or you can do a rather time consuming thing and open alpha numbers and delete the number on each texture leaving a clear 32bit tga and then place a 1 pixel dot and save.
I did that when I made some MR&T SD40s, but it took so long to do a fleet of 25, so doing a fleet of about 40-50 WSOR ones is too time consuming. I'd rather have ARN ones.