I'm not exactly sure how you do it but I remember doing it in the past when I needed to edit the speedcams. I seem to remember doing a Google search for the coordinates of the location that needed editing. Or I believe when I did a search on the program for a location, there was a way to also see the coordinates of that location - sorry I don't remember how. Write down those coordinates and delete the entry from the speedcam txt. Plus I do believe there is a skin [no, I don't know which one] that gives you the opportunity to delete cameras.
This one worked pretty good
[Please Register or Login to download file] . I typed in the name of the city and the clicked on the location and the lat/long showed up.