You need to be plucking (when loose) or cutting away the fur every 12 weeks or so. Don't leave the rabbit in full coat indefinitely as the old hairs die and start to fall out, getting tangled up with the new coat coming through - leading to a world of problems!
Also, if the fur is loose as you rarely groom it, the bun will ingest wool when grooming itself and this will lead to wool blockage which is fatal. So you really have to get a strict regime of grooming going ASAP! You can do some preventative things re. wool block - feed bunny papaya as a treat, etc. Most angora books will give you more info on this.
Angoras were BRED to be groomed - they're usually pretty docile. Even if your bun doesn't like being picked up (which bunny does? They're prey animals) if it is an angora it should happily sit in your lap and let you groom it. Mine can sit still over an hour, even though she's generally quite wary...Once she's being groomed she's fine. They're the oldest breed of rabbit. They're used to it!
You will need to know how to turn the bun over the cut the fur on the tummy, as well. Sharon Kilfoyle and Leslie Samson''s 'Competely Angora' book is great - full of useful info. I think it's being reprinted at the moment, but you may be able to get it secondhand.
If you join the National Angora Club they can advise about grooming, too.
http://www.angorarabbits.co.uk/
Site under construction but if you join, they can help you directly.
You need to be grooming at least once a week - maybe more often. Whoever sold you this bun should have taken you through all this before they parted with it!
You can use the fibre - or sell it if good enough quality. So don;t throw it away! I'm a handspinner so I use what my bun produces - it's an expensive and valuable fibre so someone somewhere will want it.
Plucking is a good option too.