How to remove grants for an user for a QA collection plan.

Hello,

I'd like to remove the grants for an user about a quality collection plan.

The user "John.Smith" is enabled in the "Define User Groups" form for an User Group that has full access to the QA plan "ABC". If I remove the flag "enabled" for that user, I'd expect that John.Smith is no longer granted for the QA plan "ABC". But it doesn't happen. Even John.Smith is not assigned to any other User Group that could contain the same grants.

Does anybody know if this is a bug, or I'm missing something?

Thanks.