deleted data keeps reappearing on my GPS device


I use BaseCamp to copy tracks from my Garmin GPSMAP 66i to my PC, rename them and store them in different folders before deleting them from my device.

Whenever I reconnect GPSMAP, I see  deleted tracks reappearing again. It seems that I *must* delete them from the GPSMAP itself to clear them from the device.

Is there any other way to keep my device internal memory clear?

How can I make changes made from basecamp persistent?

Thanks,

Andrea M