This has been brought up many times and nothing ever done about it.  

vStyler and I send skin updates regularly to each other and other testers...we even delete our own skins if there is a need to and reinstall backup versions.

We send updates to customers.We ALWAYS tell them...dont forget to uninstall old version before installing new.(many will neglect to do this,we sometimes forget and we are right in the damn middle of discussing it  )

But a simple 'delete this skin' from wbconfig isnt enough...more often than not,it leaves the folder either empty,or with 1 or 2 fonts in it.(sometimes not being used by the current skin so it aint that)

Attempting to install the skin,WB renames it and no skin shows in the skin list.Sometimes it hangs so bad while attempting to install,you have to reboot...to a blank skin...if your lucky.

So you go into WB folder and attempt a manual deletion...werks sometimes,others REFUSE to delete...so now you cant get the update to install at all without a reboot.(one folder was completely empty...and would NOT delete)

We have come to the conclusion that we should NEVER update a skin because half of the people will see no difference or it will even hang their pc.

Unfortunately,skinners dont have the option to NOT update while creating...its part of the process.