From Signitic, you can make one or more employees "disable".
Access the "My users" menu, from the left side menu of the home page.
From the menu "Users" accessible from the left sidebar, select your users with the checkbox on the left of each row or filter your users with the list buttons on the top.
Then click on "Disable" from the grouped action bar:
Hit the confirm button and it should do the trick!
Notice: Disabled users do not consume any licence.