Updated: Feb 20, 2018 by Pradeep Gowda.

Mac Texlive. Update using Tex Live Manager

sudo /usr/local/texlive/2011/bin/x86_64-darwin/tlmgr update --self
sudo /usr/local/texlive/2011/bin/x86_64-darwin/tlmgr update --all

With TeXlive the themes are located in $ROOT/tex/latex/beamer/base/themes/theme where $ROOT should be either the output of kpsewhich -var-value TEXMFHOME or kpsewhich -var-value TEXMFLOCAL depending on if you want to see it for all users or not. – src