I've got this version on jruby in Windows 10:
jruby 1.7.13 (1.9.3p392) 2014-06-24 43f133c on Java HotSpot(TM) Client VM 1.7.0_80-b15 [Windows 8-x86]
The JVM could not be started. The maximum heap size (-Xmx) might be too large or an antivirus or firewall tool could block the execution.
No commands seem to work for me, at the end I had to do it through a specific software design for this kind of issues: http://www.perfectuninstaller.com/