You can use a drum deheader.http://www.grainger.com/Grainger/items/3AY68
They are a little pricey but if you could find someone in your area who has one maybe they would cut the head off the drum for you. Don't really know what kind of business would have one -- maybe welding or fab shop.
Depending on what was in the drum - and this is very important - you could have someone cut it off for you with a cuttoff wheel of some sort. If it held something flammable the drum deheader is probably the way to go. You don't want to use anything that will cause a spark if the drum held anything flammable. I seem to recall a news article recently where some dumb a$$ was cutting the top off an old kerosone drum IN HIS APARTMENT no less to make a barbecue and it blew up and started the apartment on fire.