Hello there,

I asume you are trying to delete a directory? and it is owned by root?
if that's the case, try this:

open a console type "su" without the quotes, hit enter and use your root password,
now, if you successfully logged on as root, lets say if I wanted to delete "/home/John/test/gd"
use this:

rm -rf /home/John/test/gd hit enter

Be sure not to delete "/" that will delete your whole disk

weedje