I think the fee is $25. If you call them and want to switch to another one of their hotel offerings, they may waive the fee but in general, you have to cancel and then rebook. dizzyami is correct in saying the hotel would not be able to help, you must go through travelocity or expedia.
I have booked many times with both and have always been happy but once I did find a much better rate for DLH somewhere else and the savings was great enough to warrant paying the $25 to cancel!
The two are sometimes different in strange ways. For example, both offered the DLH view rooms that I booked for Nov with the 4th night free deal but only travelocity allowed 5 to a room, expedia did not. It pays to shop around!