I installed the morocco topo map but I installed the full thing i.e. contour lines as well. I want to wipe it and reinstall the roads only - how do I remove the existing installation from the zumo?
If you look at the Garmins internal drive using Windows Explorer you'll find a file called GMAPSUPP.
This is the extra maps you've loaded. You can delete it here or as said before just reload the maps you want and this will be overwritten using the new maps.