Hi gosu. The switch you’re after is /CLEAN
That will remove the files/registry keys associated with outdated JRE versions.
There is no switch that allows you to run the uninstaller for all previous versions. It was removed because it could inadvertently remove a necessary version. This is caused by Oracle’s decision to maintain JRE 1.6.x, 1.7.x and 1.8a.x at the same time.
The GUI removal wizard will let you uninstall previous version en masse.