Pages created with a forbidden character cannot be easily moved or deleted. See Help:Page naming.
An admin can do this using the following instructions.
Server side solutions are given here: http://web.archive.org/web/20120112150328/http://www.mediawiki.org/wiki/Manual:Short_URL/Ampersand_solution - valuable if there are many pages.
Solution for admins without server access (tested for "&", presumably works with other forbidden characters):
- Export the page(s) with Special:Export - this will work in spite of the "&". Save as xml file.
- Open the xml file in a text editor.
- Look for the <title> tag
- Edit the title, removing or replacing all forbidden characters, e.g. "&" with "and". Save the file.
- Import with Special:Import. View the page to confirm that it has been imported successfully.
- Delete the original page with the bad title. This is tricky:
- Copy this url: https://www.appropedia.org/w/index.php?title=TITLE&action=delete
- Replace TITLE with the bad page title
- Replace spaces in the title section with underscores: _
- Replace the ampersand - & - with %26. So to delete a page called "A & B" you would use the url https://www.appropedia.org/w/index.php?title=A_%26_B&action=delete
- Replace other forbidden characters - this hasn't been test here, but it's likely that you can replace them by %nn where nn is the hex code given in this table of printable characters for that character.
- Now you have the url, enter it in your browser, hit enter, and confirm the deletion.