Problem deleting unwanted ships and ship templates

I recently wanted ro rename my ship designs for convenience as I have too many of them and some of them are repeats of the same or similar designs. Unfortunately it seems like I ugraded some of them too many times. When I try and rename them in the ship designer it often gives me two versions of the same shape, one with the wrong image (although often not when I sample using the design to create other designs). When I then try and delete the old versions it once again gives me two versions or deletes different ships. I figured I could change the XML files but they don't seem to have any relevant information. Basically it seems like I have to change the shipconfig files since this is where the upgrade information is but there doesn't seem to be a way to do this.

Any help or advice much appreciated

Cheers...