The pinned FAQ says it is not possible to change your STG number. Mine is currently set to the UK, but I'll shortly be moving abroad making the UK number redundant.
How do I change from a UK based STG number to one based in another supported country ?

Please go here http://support.skype.com/?_a=tickets&_m=submit and submit a ticket with full details to the correct department. Scroll down to the bottom of the page and click submit / send. Note that a reply can take a minimum of 3 working days.

Check your SPAM settings and the SPAM folder at the server for replies from Skype.

Ike

Sorry, I don't really understand your response - it kind of looks like an auto-reply.
Are you telling me that this forum isn't the correct place to raise my query ?

The Community (Forum) is not an Official Support Channel for help from Customer Support. You need to submit a ticket to Support via the link in my previous post. Read more info about the Community here.

However, if you do not receive a reply from Customer Support within 4 working days, we can forward your issue to Support.

Ike