Way to prevent all users accessing Essbase and planning application

Hi everybody,

we are upgrading from Hyperion 9 to Hyperion 11, so to do that, we built a new environment to have both production in parallel. Now, we are preparing the cut-over and we want  to prevent all users accessing the old production (version 9) while we are testing the new one (version 11). We have a round a 100 of users with different grants and privileges.
So, please there is any easy way to do it?

Thanks

Mel