Did find it in a post by "le bouch":
Turns out you CAN overwrite the Factory groups, with whatever’s currently in the User groups. Here’s how:
"You can easily copy the programs from the user locations to the factory locations using the following steps.
Hold the RELEASE button and press the 3 button.
The record button begins to blink, press the RECORD button to copy the patches from the user locations to the factory locations.
The record button light turns off indicating the process has completed".