Since we have already created an install Application for Firefox, we already have the code available to do the uninstall. The .MSI contained the install and uninstall command lines in the Application. Select the Firefox Application, and in the window pane below select Deployment Types. This particular Mozilla Firefox Uninstall is for version 18.0.1, if you need the Uninstall Product Codes for other versions See This Post.
Double click the Mozilla Firefox Deployment type and the following screen will appear. Select the Programs Tab and you will see the Uninstall program Command Line complete with the GUID of the previously installed Mozilla Firefox Application. Keep in mind that the only Firefox deployments that will be uninstalled will be the ones created with this exact application.
Copy the command line for the uninstall and keep it for the Firefox Uninstall Package that we will create. Go to Software Library\Overview\Application Management\Packages right click on Packages and select New Package. Give the Package a name and Click Next..
Accept Default Standard Program and Click Next..
The next screen is where you will paste in the Command Line code from the Application for the uninstall. You can also select these other installation options and Click Next..
Here you can specify requirements for the package..Click Next..
Confirm Your Settings, Click Next..
The Create Package and Program Wizard completed successfully, now you can close this out and Deploy the Firefox Uninstall Package.