I suggest you try to post this question at click here they are very helpful there and are the experts were Sat navs are concerned !!
Regarding deleting some favourites I would think you would do it in tomtom home !!
I must warn you to make a back up copy of your sat nav before you do anything !! also do not depend on Tomtom home to back it up correctly !!Make a back up in windows !!
The above site gives a full explanation on how to do it if you do not know