When you use Geary with a Gmail account, Geary lets you archive messages. The Archive toolbar button archives the selected conversation(s). Archived messages appear in the All Mail folder.
With other mail servers, you can trash or delete, but not archive, messages. To move one or more conversations to the Trash folder, select them and press the Trash button on the toolbar. To permanently delete the conversations, hold down Shift and press the Delete button that appears in place of the Trash button.
Delete is not available from every folder, such as Search. Delete is also unavailable for Gmail. For Gmail, Trash will move messages to the Trash folder on the server, where the user can then manually delete them. The server will automatically remove trashed messages after 30 days.