Yes,
De-activation of the project will make the users to log-off from the project.
ARE YOU SURE, YOU GOT THE MESSAGE "logoff all the active users of PC .?" (usually it makes for that project only)
There is nothing to worry about this. Mandatory Activity.
But make sure you keep inform the users who had login to this project (Site Connections) OR you can plan a scheduled time for such activities.
Go Ahead....!!
