For me was posible xD
I stopped ALL vmware services, not only SSO, all of them (vcenter, web interface, etc...), deleted JRE folder, and started the upgrade without problems.
If you uninstall SSO (I tried this also before knowing the JRE issue), , and install again, you must configure it, and after that, vcenter fails because the data on the SSO installation doesn't match or something like that....
Nothing else....
Regards.