It depends on your definition of “kill”.
OpenSolaris -> Illumos
Hudson -> Jenkins
OpenOffice -> LibreOffice
MySQL -> MariaDB (not killed, but forked out of fear it would be)
And a non-Oracle example:
Node.js -> IO.js (arguable - forked because Node dev was stagnant, eventually merged)
All those had communities outside the main company long before they "moved out". What's the percentage of external contributors to GitLab? 1%?
Hmm what about the Blender project, would that one count?
I admit it's difficult to come up with examples, though I don't know of any failures either. RethinkDB has been sort of a failure, but it was never very popular to begin with.
I'm not challenging necessarily, I legitimately am interested in examples.