Airmail App makes use of a unified inbox. This means that the main inbox, contains all the messages of all the different mail accounts.
The app will automatically open in the Unified Inbox. It can also be accessed from the Sidebar Menu by tapping on All Inboxes
Remove account from Unified Inbox
1. Tap the menu icon in the top left corner on the app, which will reveal the menu.
2. Tap on the email account you would like to edit.
3. Tap on unified inbox to disable.The button will turn to grey to confirm the account has been removed from the unified inbox.