[WiX-users] Force unistall of msi package inside burn updating process

I have a burn package that contains an msi package of a third party company that I can't modify.When I update my burn package, as there are some problem in updating this msi package from an old version, I need to force uninstall of the old msi package, delete all the folders and files, and

[WiX-users] On uninstall, group is not removed from user

I have the following markup to add an existing user to a group: Fragment util:Group Id=AdministratorsGroup Name=Administrators / ComponentGroup Id=ProductComponents Directory=INSTALLFOLDER Component Id=cmpExistingUser