but this means I'll be uninstalling the applications for the entire server.
What I meant was, I want to let my clients with domain (A) use eg. phpbb forum, at the same time, I do not want to let my client with domain (B) use php forum !
Doesn't plesk allow the administrator selectively disable each of the power pack applications for each individual domain, instead of uninstalling the power pack applications altogether from the server ? Obviously, this uninstalling from the server mean all domains will not the option of installing the power pack apps !