Q: Where can I manage Plesk updates and upgrades?
A: In Plesk, among others, there are Power User view and Service Provide view. In case of Power User view follow the steps bellow to get to upgrade management screen.
*Screenshots taken from Plesk12.
After logging in to Plesk go to "Server" tab
You can go to update management screen by clicking "Updates and Upgrades" in "Plesk" section.