It's quite strange. Plesk autoinstall offers to install components but uninstall or re-install is not possible.
Right now i have problem starting "Parallels Premium Outgoing Antispam" which is installed and i have licence for. But i just get the message: "Protection : Not active. There are some problems that prevent the service from being started."
I really don't know what to do. I might be that i uninstalled it manually or in some other way few months before but i don't remember.