To remove the user, you must perform the following steps:
1. Choose "Manage users" from the main menu
2. Click on the user you are interested in (in the area where there are no buttons)
After that, the editing page will open.
To remove the user, click on the button "Delete" ( ) in action menu. You will be asked to confirm the deletion, so click "Yes". Then you can click "Back" ( ) to return to the previous page.