Can´t delete Internal Memory items in Basecamp

Basecamp has, (in my opinion), an annoying feature which it's predecessor Mapsource diddn't have - it's database. Mapsource was basically 'empty', when you entered it, you would open a file, edit it and save the edited file, if you downloaded a file from a Garmin unit, edited it and sent the file back to the unit, that was the end of the process.

Basecamp has a database of what it thinks should be on your unit and although this is sometimes useful, it can also be annoying, I quite often disconnect all Garmin units from the computer, startup Basecamp and delete all items in it's database, (this will not delete any exported files that are resident on your computer), highlight and delete all routes, tracks and waypounts from the lefthand column so that Basecamp is 'clean', then plug in your Garmin unit and Bascamp will display a 'true' picture of what is on your unit