Selling of asset has no particular place however, where you sell depends on where that token is listed Also, if the token is not listed where you like to trade will you keep the token. Have it at the back of you mind that sale of token depend on where it is listed.
Selling is not a problem earning is a problem. Anyway if you want to sell your coins, it is right that you can sell your tokens in that exchange where it is listed. If your tokens have priced and you want to sell them it is better to convert them into bitcoin and then sell it. By this way you will find buyers easily and comfortable and you will have a record of your transactions.