Why would you ever want to leave your Moosend account?!?
Well, you must have a good enough reason to want to log out, so just follow the two steps below and you're as good as done:
1. Click on the Account button, located on the left side of your Control Panel page. 
2. Click on the Logout button on the menu that appears. 
And don't forget, we'll be really happy to see you log back in your Moosend account again soon!