Just curious...but what would be the point in removing it? I can't recall any situation where I thought it was in the way of anything.
I've never tried to run it w/o the drip pan in place...it does a ptretty good job of catching any errant drippings and I just wait until it cools off and before I use it the next time I scrape any build-up out with a plastic putty knife.
Over the past weekend I did the mondo meat smoke in my big block. I loaded it up with 4 packer cut briskets ranging from 9 to 13 Lbs. When they were done, it looked like a grease bomb went off. The water pan and drip pan caught a good bit of it. I Don't think I would ever use it without! I Need to look into foil coating both pans to make clean up a bit easier. Thank God for power washers!