On Albumo and FeatPics, all it took was an email to get the account wiped wholesale at both places.
DT is a different story. There I just wanted a single image deleted from the database and they would not do it. The image is now in "disabled land" for an indeterminite amount of time. When I inquired about deletion, they gave me somethong about legal and liability issues, etc. Understandable, but's not like I was looking to delete 20 best sellers or an an account, just one image that never sold, that I wanted to reroute for different use. I figured it was safer to delete it than have it get reposted by me for sale in error.