I can't delete built-in shortcut keys. If I in Tools|Customize|Keyboard delete a shortcut key and click ok, it's back when I restart LibreOffice. I can only replace the shortcut key, not delete it. It is a problem if I want to use a specific key as a global LibreOffice Shortcut key. If that key already is in use in Writer Calc or whatever it takes precedence over the global key.
This one might be related to "Bug 40578 - CONFIGURATION: Tools-Customize-Keyboard changes should be persistent".
[This is an automated message.] This bug was filed before the changes to Bugzilla on 2011-10-16. Thus it started right out as NEW without ever being explicitly confirmed. The bug is changed to state NEEDINFO for this reason. To move this bug from NEEDINFO back to NEW please check if the bug still persists with the 3.5.0 beta1 or beta2 prereleases. Details on how to test the 3.5.0 beta1 can be found at: http://wiki.documentfoundation.org/QA/BugHunting_Session_3.5.0.-1 more detail on this bulk operation: http://nabble.documentfoundation.org/RFC-Operation-Spamzilla-tp3607474p3607474.html
this problem was fixed, now it is not reproducible, in LO 3.5.0 change status to WorksForMe Please, if problem appears again, change status to Reopened