Any Products that are listed as Yes in the Uninstallable column are available to have an uninstall package created in a 3 step process exactly as the update packages in blue.
For Products listed as No in the Uninstallable column you must customize the execution flow script to successfully uninstall the product. This can be done by starting the SPS Package Creation Wizard and selecting the Edit Package Content check box in Step 1.
If you have an SPS XML template you can import it by clicking Import Package in the first step of the wizard. Once this is completed, all the fields in the wizard will be automatically populated, including the execution flow script.
Special attention should be given to the files mentioned in the execution flow script. These files can be files originally provided by the SPS template creator or they can be dynamically downloaded.
Important:You should only import SPS packages if you trust the author of the package and the source from where you downloaded/obtained the package.