Try
LocalBitcoins, you can sell it to Western Union on there, depend on seller. But be careful with some scammer on there.
Or go to
Currency Exchange section and create thread if you want sell it with western union. Make sure use escrow.
Wow! I never would thought that it would be okay to sell it in western union? This would be amazing thanks a lot that I got to see this website it is a big thanks
Edit:but this reply would say thisss...
There are so many ways, you can simply sell your BTC to someone in exchange for USD and the person will send the fiat currency through western union. Ya, just like other users might have stated, buyers can be found in localbitcoin but you need to be super careful cause some of them tends to be fraudsters in disguise. Try and get a buyer around your vicinity and request for face to face transaction.
Reading this that it will not be helpful for Western Union to help you in selling your bitcoin

So here I would suggest use your wallet, you electronic wallet that is an exchange that is much easier and a specific wallet contains features where you could widraw your bitcoin income to USD like my wallet in my country that got different options where you can pick a bank to widraw and I can see thatbis much safer.