Frank --
I've been
digging into the same issue recently, but not specifically via GAM. Google doesn't expose an explicit API to reset sign in cookies, but the consensus is that resetting the password for an account will invalidate the current cookies within 60 minutes.
Google's language on
one of the support pages is "
It can take up to 60 minutes to log out the user from current Gmail HTTP sessions. The logout time for other applications may vary."
Other admins have discussed that they think requiring the user to change the password at next login will also force (eventually) the resetting of current cookies.
I'm yet to find a definitive statement, or process that will work quickly (other than using the Admin UI to do it via the checkbox).
--Nick