Silently uninstalling Java
There are three Java uninstall packages available in the Package Library. Each package uninstalls Java installations in a particular family. The three families are: Java 6, Java 7 and Java 8.
Each uninstall package will kill browsers and any currently running Java processes before proceeding to the uninstall. This is generally considered a best practice as you can encounter some nasty errors if a target computer has Java actively running at the time of either an install or uninstall.
Avoid putting your users through too much distress by scheduling the deployment for after hours.
The install step (Step 3 below), which is what will install Java 7 for most of your machines, simply calls a .bat file. This file simply searches the Uninstall keys in the registry and uninstalls all instances of Java 7 that it finds.
Which computers have Java installed?
Sure you could deploy your uninstall package out to any and all computers in hopes of catching the ones that have Java installed. Or you could save yourself a little time and get right to the computers you need to. After an initial scan PDQ Inventory Enterprise customers can use the Collection Library to drill right down to the computers they need.
When you highlight a package and click Deploy Now, in the deployment window you'll have the option to deploy to PDQ Inventory where you can select the collection containing computers with the particular version of Java you wish to uninstall.