Are you looking for Server Management >> Logon Policy?

singh,

myArch-man is correct.  The System > Logon Policy function will allow you to define the period of time before the session is automatically closed; however, this function is available for On Premise installations only.  If you are using the Cloud (SaaS) offering, you will not be able to define the Log on Policy (or even access the function) as the configurations on this page impact all tenants on the server, not just those technicians logging on to your tenant.

thanks myArch-man