Currently the best way to install LaTeX on an OS X system is with the MacTeX package. But removing MacTex is non-trivial. Here’s what I came up with, based on instructions here:

NOTE: These instructions assume that you’re using only the ghostscript and imagemagick versions from MacTex. If you are also using macports or homebrew or custom-installed versions, you will almost certainly need to uninstall/reinstall those.

Remove the bulk of MacTex, some Tex stuff from Library, and the GUI applications:

sudo rm -r /usr/local/texlive /Library/TeX /Applications/TeX

Remove the preference pane:

sudo rm -r /Library/PreferencePanes/TeXDistPrefPane.prefPane

Remove the custom version of ghostscript. This should all be on one line, be careful with copy/paste:

lsbom -sf /private/var/db/receipts/ | sed 's#^\.#/usr/local#' | tr '\n' '\0' | xargs -0 rm

Also this final ghostscript detail might be needed:

sudo rmdir /usr/local/share/ghostscript

Remove the custom version of imagemagick:

sudo rm -r /usr/local/bin/convert /usr/local/etc/ImageMagick /usr/local/lib/ImageMagick* /usr/local/share/man/man1/convert.1

Remove some ghostscript and imagemagick symlinks. Again, this should all be on one line, be careful with copy/paste:

sudo rm /usr/local/bin/gs /usr/local/bin/texdist /usr/local/share/man/de/man1/{eps2eps,ps2pdf1?}.1 /usr/local/share/man/man1/{eps2eps,gs?j,gsdj500,ps2pdf1?}.1

Remove the BOMs and plists:

sudo pkgutil --forget org.tug.mactex.texlive2012
sudo pkgutil --forget org.tug.mactex.ghostscript9.05
sudo pkgutil --forget org.tug.mactex.gui
sudo pkgutil --forget org.tug.mactex.imagemagick-convert-6.7.6-9