Hi Luis,
Here are the steps
Deleting a Music On Hold Audio Source
Perform the following procedure to delete an existing Music On Hold audio source.
Before You Begin
If you delete an audio source that an item such as a device pool or an individual device uses, Cisco CallManager displays a warning message. To find out which device pools or devices are using the Music On Hold audio source, click the Dependency Records link from the Music On Hold Audio Source Configuration window. For more information about dependency records, see "Accessing Dependency Records" in the Cisco CallManager Administration Guide. Before deleting a Media On Hold audio source that is currently in use, you must perform either or both of the following tasks:
•Assign a Music On Hold audio source to any device pools or devices that are using the Music On Hold audio source that you want to delete.
•Delete the device pools or devices that are using the Music On Hold audio source that you want to delete.
Procedure
Step 1 Choose Service > Media Resource > Music On Hold Audio Source.
The Music On Hold (MOH) Audio Source Configuration window displays. The Music On Hold Audio Source: New (New) title displays with a Status: Ready indicator.
Step 2 From the MOH Audio Sources list, choose an existing Music On Hold audio source.
The Music On Hold Audio Source title displays the name of the chosen Music On Hold audio source. The fields below the MOH Audio Source title display the previously defined values for this Music On Hold audio source.
Step 3 Click the Delete button.
A popup window displays the following warning:
You are about to permanently delete this Music On Hold Audio Source. This action cannot be undone.
Continue?
Step 4 Click OK.
The chosen Music On Hold audio source no longer appears on the MOH Audio Sources list. The Status changes from Ready to Delete completed.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/3_3_3/ccmfeat/fsmoh.html#wp1028245
Hope this helps!
Rob
