Go to MENU>PROFILES>Pick your profile e.g general>CUSTOMIZE>TONE SETUP>SIM1 INCOMING CALL>Scroll down to slot 26, click the song that is currently allocated to slot 26 and click ok on it>DE-SELECT. This will remove the tone from the list.
To place a new tone in slots 26-30 follow these steps
FILE MANAGER>OPEN>MY MUSIC (or wherever your intended tone is)>OPEN>Select the track>OPTIONS>FORWARD>TO USER PROFILES