How to remove original map of Zumo 210

I like to replace the original internal map of my Zumo 210.
When I look at the files and folders inside, I see that the total memory is 4GB.
2GB is used by the map, and the rest is free.
The visible files on the Zumo only take a few hundred MB. So the map is not visible.
Somehow Garmin made it invisible.
Making all files visible in Windows mapoptions does not help.
With the help of Basecamp or mapsource I can not replace it.
It should be possible because last year I got an update of this map directly installed into the Zumo by the Garmin website.

Is there a way to replace the original map with a newer one without having to use an axtra micro SD card ???
Or is there a way to make the original map visible, so I can replace it by a new one ?
In the diagnostic settings there is no setting for that (only battery, screen, audio).

maybe >>>this tutorial can help you too

Found it !!!
I forgot to uncheck the hiding of the protected system files in folder options.
Problem solved.