I had a Cod4 server that I deleted. Afterwards I couldn't delete the server from my favorites. The link to delete the server is not clickable and the page gives me a message saying the server could not be scanned.

If the server was automatically added (GameServers.com servers or GT Premium servers), the delete button is disabled.

I'm guessing you mean http://www.gametracker.com/server_info/208.167.250.234:28960/

The server will be automatically deleted by the system after extended downtime. This amount of time it takes to delete the server varies based on how long the server has been on the website, so since yours does not seem to have been on for very long, it should be removed quicker than others.