I found this in my Pro-95 manual, perhaps yours is similar:
CLEARING TALK GROUP IDS
1. Press PGM then TRUNK.
2. Press FUNC, UP or DOWN to select ID memory.
3. Press FUNC then CL.
CLEARING ALL TALK GROUP IDS IN ONE BANK
1. Press PGM.
2. Press TRUNK to enter a talk group ID memory mode.
3. Select a talk group ID bank using FUNC, UP or DOWN.
4. Press FUNC then 6. Confirm list clear? 1=YES Press other key for NO. appears.
5. Press 1 to clear all talk group IDs within a bank. List cleared appears.
To cancel the deletion, press any key except 1. The scanner returns to the talk group ID memory mode.
Hope that helps.