There is no simple answer. If the aggression is genetically determined the "long term" answer is to move the bees out to an isolated spot and requeen them with a queen from a gentler strain and not move them back until temperament has considerably improved (can take a few weeks although occasionally replacing the old queen with a young one pumping out loads of pheromone can quiet them down very quickly). In the meantime there are a few things to consider. Many "so called" stroppy colonies are often not as described as the beekeeper is "the problem" opening them up too often and at unsuitable times eg when all the bees are at home eg in cold windy weather, just before thunderstorm etc or they were clumsy or heavy handed with jerky manipulation or used too much or too little smoke and letting them get out of control. ie is is aggression or defensive behaviour being witnessed ?
One useful technique with badly behavioured bees is to first move the hive a few yards away leaving the supers on the original site to pick up the fliers. A bled hive is easier to inspect as far less older bees will remain in the brood chamber ( and these are the potential stingers) . Of course get properly protected inside bee -suit, wellies etc and make sure there are no members of the family, public etc are out and about, Don't expose too many frames at one go by covering frame top bars (I use the removed dummy board rather than a cover cloth). Only check the minimal number of frames needed to work out what is going on (about four if often enough ) . Only opening the hive when absolutely necessary and even then keep all manipulations down to a few minutes. Stand behind the hive with foliage behind you so they can't "pick you out" against the sky . Years ago I came across a beekeeper that popped pieces of dried puff ball into his smoker (to anaesthetise them)
Lots of other things but getting tired of typing now and I have had a long day. I'm sure others will come up with other possibly more useful tips.
If you do have to kill them (they would have to be pretty bad to justify that) don't use petrol (the thought of beekeeper with can of petrol in one hand and lit smoker in the other!!") Spraying bees with "washing up" water kills them fairly well and doesn't contaminate the combs