Remove Unsynched Custom Ringtone from Ringtone Option Under my Device Tab?

I went to load a custom ringtone into my itunes to put onto my iPhone 3GS. I got an error message saying it could not be synched as there was not enough room on device. I deleted some songs, and plugged it back into my laptop. I tried to synch the phone but it still wont synch nor delete the ringtone from the under Ringtone that is located under My iPhone tab plus it wont show up on my iPhone. Please help!! I want to remove it and to reapply it after I make space for it again!