You can sell your crypto in a quick by just selling it in a exchange and make sure you should use a trusted and reputable exchange. You can also do the P2P but the best place to sell cryptocurrency is in a trading platform.
I've unique way to sell my crypto in quckly way to fiat or my bank though service online like local exchanger crypto to fiat. They available for 7/24, everytime anytime and where you are. I just need follow procedure, after my cryto sent then take a block (confirmation), then in minutes their will process, then finally i get my money in my bank accounts.
The quickest way is through exchange you could instantly sell it if the crypto that you want to sell already have a buy order or demand in the market.
By far, the best and fastest way to sell cryptocurrencies is through Exchanges. Not only it's more quick, but you'll also get some support if something wrong happened. These exchanges are reputable enough and is more reliable ti transact with.