Garmin Nuvi 250?

I am re-arranging the catagories I added to my sat Nav Garmin nuvi 250 and want to delete some of them. How is this done I can't find anything in the user manual on this and Garmin uk seem to be email shy as I've had no reply. Connecting to my computer I don't see any file/folders other than operating ones the only others are the photo,s Ive put on it.
Thanks in anticipation.