How can I edit the permalinks?

Hi,

I have a page on my website, http://www.coffeetrekkers.com, called 'Valentines'. The permalink says the last bit is 'valentines-2' but I just want it to be 'valentines'. I go to the page in 'pages' in admin, click on the 'edit' button by the permalink, change it to 'valentines' then click OK and nothing happens - it is not changed. I tried it clicking 'update and publish' and still nothing.

I did have a page a few weeks ago called 'valentines' but I deleted it as I'd got it all wrong. Could that be why there are problems?

What am I doing wrong?

Thanks,

Damian