Twenty Ten/ Trouble deleting slider picture!

Hi there!

I am having some trouble deleting a “ghost” picture in wordpress and the theme Twenty Ten. Here is the story:

I’m building a wordpress site for my cousin and her charity project. I am using the basic theme Twenty Ten and the default slider in the theme. I have uploaded some custom pictures for the slider using the dashboard and built in upload tool in wordpress. But my cousin realized that the picture was wrong thus I deleted the picture from the server using FTP-connection (because there are no delete function i wordpress for that theme).

But the picture or rather the empty thumbnail spot in the wordpress tool is still there and the slider is showing a faulty picture when browsing on the site some times.

The site is http://www.swamvolunteering.org.

Please help us!

/Max