There are many good extensions for LibreOffice. You can find it all on site https://extensions.libreoffice.org/. I want to tell you about the best from it.
So, there is an enhancement 85976 about adding of Remove Duplicates feature to LibreOffice Calc. That is really useful function and LibreOffice Calc isn't having it now.
However, there is Remove Duplicates Fast extension that adds need feature to Calc. It's a fork of another extension Remove Duplicates.
RDF allows you delete all row duplicates from selected range using values from one or more column. Just download it by link above, install and use it from Data menu.
Thanks to Mike Kaganski for great code writing.