Firstly, I'm assuming you want to carry out maintenance on one central database which all these user are acessing.
There's no easy way I know of.
You could try playing round with timer intervals to make the database quit after x hours of inactivity. You could also use this OnTimer event to make all database log out at a certain time in the evening.
But probably the best would be to create a centrally accessible table(tblAppAccess) with one record and one field (AccessAllowed) of type Yes/No. Default this to 'Yes'
Set the Timer Interval on the main form of your database to something very frequent, like every 30 seconds. The set the OnTimer event to look up this table, if the value of 'AccessAllowed' is set to 'No' then run the code
which will close Access.
When you want to do your maintenance, you set the value of this table to 'No'.
Also, I am assuming that there is a main form opened when the user open the database, and that this stays open throughout their session.