ALso, when doing an install, if my memory serves me right, there is no need to add a "custom" user, and then assign whatever rights. The "first" user added to a "buntu-based" system is by default placed in the sudoer group, and is the admin for the device. Other users added are by default "non-admin" or just plain users. It will be cleaner to fully purge OO as others have said, before installing LibreOffice from the Lubuntu Software Center (or by using something like Synaptic which should work better on Lubuntu anyway).
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