To block a user from the VIGIE portal, go through the following steps: 

Step 1:  In the main menu, on the left side, click on Users Management.

Step 2: Select the user you wish to block. A side window will open with the user's data.

Step 3: At the bottom of the side window, under actions, click Block user. 

Step 4: You will get a warning saying "Are you sure you want to block this user?". Click on the Yes option.

Example of how to block a user: