Financial challenges is what can make people to sell there Bitcoin and we can't judge them because we don't know what they are passing through. Honestly sell your Bitcoin now is not a good advise because the market is still down and he should wait for when the market gain some momentum so that it will be profitable for him. If he chooses to sell, then there are many exchanges he can use to sell, transferring the Bitcoin to tye exchange after registering there. He can also sell his Bitcoin through P2P in the forum if anybody is interested in it using an escrow service.