In order to delete a Session Host VM please login into the Workspaces portal and perform the following steps:
1. Click on the Workspaces to which the Session Host belongs to and go on App Store.
2. Move all the Apps from right (Published) column into the left (Available) column. See the screenshot below:
3. After all the Apps have been moved into the left column you will be able to delete the session host.
4. Go back to the Workspace Dashboard and locate the session host you wish to delete and double click it.
5. You will now be on the server properties page. In the lower left corner, in the Actions pane, click the Delete VM button.
Caution this action cannot be reversed! Be sure you really want to delete the server.
6. A Workflow will begin, when the Workflow has successfully completed the server will be deleted.