How to delete a picture of catagory on Virtuemart 2.0.22?
Please be more specific. A single picture for a category or all category images?
http://forum.virtuemart.net/index.php?topic=79799.0
all category images
You could edit category template (delete category image there). Use template overrides for doing this - Doc section of virtuemart.net or Sticked threads in Template forum section.