If you are a not a bee keeper and you are reading this, the answer to your question will be to search on the internet for your local beekeeping association. On their website you will find details of who to call for swarm collection in your area.
If you find bees living in the structure of your property this is a very different situation to swarm collection. A hobbyist beekeeper will not be able to help with colony removal like this as they will not have adequate insurance. There are profession companies that can help with the removal of these feral colonies, do check they have adequate public liability insurance. They will ensure the all the comb, honey and all of the bees are removed. This can be very costly so before you begin down this road do consider if the bees really are a nuisance. If you look on the BBKA website you will find links to such companies that can give you advise and provide you with quotes for the removal.
If, however, you are a beekeeper and you are reading this the answer is of course that you should collect the swarm yourself! Your bees are your responsibility and if they swarm you should try to see where the swarm goes and deal with it yourself so that it does not become a nuisance to the public or your neighbours. If you are a new beekeeping and don’t know how to collect swarms speak to your mentor if you have one or seek help and guidance from your local beekeeping association. Once you have seen how to collect swarms you will have confident the next time to do so on your own.
If you are a known beekeeper in your village or town you will probably find that you will be called for every swarm that shows up in your area and they will all believe they are from your bees even if they aren’t! I would say that all beekeepers have the responsibility to do what they can to assist anyone that calls about swarms. If you are unable to collect the swarm yourself then put them in touch with someone who can help them.