Erasing a Tool from the Core and Restoring the Original Icon.
Activate ICON in the ASSIGN CORE KEYS menu screen to erase a Tool from a Core key and restore the original icon. Activate Clear Key Contents to clear everything from the key.
To Erase the Tool and Restore the Icon
1. Go to the Toolbox. Activate ASSIGN CORE KEYS. 
2. Activate the key on your overlay that contains the Tool you want to erase.
3. Select ICON in the Assign Key As box.
4. The original icon is restored.
5. Activate OK.
If you want to clear the entire contents of the key so it becomes a blank key:
1. Go to the Toolbox. Activate ASSIGN CORE KEYS.
2. Select the key whose contents you want to erase.
3. Activate the Clear Key Contents key.
4. Activate OK.
The key is now blank. It has neither an icon nor any contents.