Stop the bot. Now remove all the pairs from the exchange you want to get rid of. Save changes. Now go to your profile and then to “exchanges” tab. Remove the exchange and click “Save changes”. Start the bot. In the case it’s still there, go to “Edit exchanges” and edit the exchange. Select the first option (empty) in the exchange list, and remove the api key. Save changes. If after doing this and restart the bot the exchange is still there (I don’t think so) you would need to remove it manually from config.js using Notepad or other text editor.