Basically we have users who are up at all times and there is an ETL process from 2am to 5am that needs to run that is crashing because users are using it during peak load times. The 'honor' system is obviously not working ;).
Go to your SSAS instance, expand Database, Expand "yourdatabase", Expand roles. You will be able to see the roles there. Right click on required roles and select properties. Go to Membership tab and remove the user from here.
----------
Ashish