How to Uninstall QGIS from MacOS

Question

As many probably know, the MacOS installer for QGIS is not as turnkey as the windows version. You have to basically install 3-4 sets of packages, only one of which end up in the Mac apps directory (e.g., GDAL) . If I want to completely uninstall QGIS, how do I go about uninstalling the packages like GDAL?

Answer 1

The removal is basically also a "manual" process.
Assuming you have installed QGIS3.2
If you still have the .dmg, navigate to GDAL Complete Extras, you will find there a ReadMe.rtf
(If you don't have the .dmg, just download it again if you would like to get the specific instructions for your version of QGis) Around the bottom you will find the uninstall instructions:

Uninstall

Drag GDAL.framework, GEOS.framework, PROJ.framework, SQLite3.framework and UnixImageIO.framework from /Library/Frameworks to the Trash.  
Also trash /Library/Application Support/GDAL and ~/Library/Application Support/GDAL (if it exists).

Run these commands in a Terminal:

sudo pkgutil --forget org.gdal.gdal22-framework-yosemite
sudo pkgutil --forget net.refractions.geos-framework-yosemite
sudo pkgutil --forget org.maptools.proj-framework-yosemite
sudo pkgutil --forget org.sqlite.sqlite3-framework-yosemite
sudo pkgutil --forget com.kyngchaos.UnixImageIO-framework-F-yosemite

Python

Use pip to uninstall the python components:

sudo pip3 uninstall gdal
sudo pip3 uninstall proj
sudo pip3 uninstall shapely

NOTE: These instructions are provided as copied from the documentation. If you are unsure or unfamiliar with executing commands from the terminal I would suggest getting assistance from someone who has experience in doing this.

From there its the same as usual for any non app store app, delete QGis from the Library, search Library for any other directories/files related to QGis and move them to trash.
Lastly clear trash

Link to a How To guide

Edit: For QGis 2.18, the uninstall instructions are scattered in different .rtf files, each relevant to the specific application.