While there isn't a direct setting to log out out users after idling for a set period, a suitable workaround would be to configure the logon time range for the user according to their security profiles. To set this up:
On the System tab, click Profiles.
Click Next and/or Previous to scroll to and then select the relevant Security Profile.
Click Edit, Global.
Note: Any changes made here will be applicable to the selected security profile only. If these changes are required across the system, please make them on each security profile.In the Logon Time range section, enter the anticipated logon and logout times for the user.