[Qgis-developer] How to remove PyQt5? - using QGIS2.99, Python 3.5.3, Qt 5.7 or Qt 5.8, and g++ 6.3 on Ubuntu 17.04 (Zesty) 64-bit

[gordon at shieldaig.com]

Before I ask this question on StackExchange, does anyone know how to 
completely remove the effects of using `sudo pip3 install PyQt5` as 
using `uninstall`, although it does remove a lot, doesn't seem 
completely up to the task?

`pip` is very useful.  I've reinstalled everything using `sudo apt-get` 
even tried purge options too.  I would prefer not to use a virtual 
machine, reinstall everything, etc..  I have also removed the build 
folder.  And even upgraded to Zesty.

I still either got this error
`Segmentation fault (core dumped)
python/plugins/db_manager/CMakeFiles/zzz-db_manager-15-depend.dir/build.make:72: 
recipe for target 'python/plugins/db_manager/ui_DlgAddGeometryColumn.py' 
failed

or no python support, because it does build, if I used `sudo pip3 
install PyQt5` because it is now 5.8 or other errors if I specified 
`==5.7`.

This seems like a `very very small` problem and I hope and I am not the 
only person trying to keep their system current and running into these 
kinds of problems.

Gordon

PS. I can switch everything to Qt 5.8 as I downloaded source build files 
for qtwebkit 5.7 and 5.8 and pypt5 5.7 and 5.8 but don't really want to 
do that either.  It does make the build environment more flexible.