1.    Turn off the streetpilot.
2.    Use the USB cable to connect it to the PC (to access it in mass storage device mode).
3.    Open "<deviceletter>\Garmin\GPX\“ and delete the file "current.gpx“.
4.    Safely remove from USB (this will also power off the streetpilot).
5.    Now push your finger in the lower right corner of the unit and keep it pressed down!.
6.    Push the power button to turn on the unit (still pressing down the finger in the lower right corner).
7.    Now you’ll get a prompt „do you want to erase all your custom data?“.

NOTE:  The 3rd step (deleting the "current.gpx“) is mandatory! Otherwise the streetpilot will recover the waypoints from that file.  -And also,the file will be re-created on unit shutdown.

So in case anything goes wrong during above mentioned steps (e.g. you’re not pressing the right spot in step no. 3) you’ll have to start over from step 1.

 philipp g.