[galaxy-dev] Deleting datasets from server

Hi there, I would just like to ask if I could just directly delete the .dat files from the database folder of Galaxy (or even just the tmp files). I am not allowed to delete any other file from the computer other than the ones in galaxy-dist. I have tried running the cleanup scripts, but since the disk is already full, I am experiencing some problems with the cleanup. I'm just new to using this application, so any help would greatly be appreciated. Cheers, Michelle