Windows 10

has something to do with the Python pymcsapi installation. If no Python was detected during installation the uninstall works as expected. If Python was detected during installation the uninstall doesn't work.

Needed to set the Python directory properties to secure.
Now we should be able to uninstall the Bulk Write SDK successfully if Python was detected during installation.

For QA:
Try to install and uninstall the bulk write SDK on 4 configurations of Windows 10

1. with no Python installed
2. with Python 2.7 installed
3. with Python 3.7 installed
4. with Python 2.7 and Python 3.7 installed

Confirm for all 4 configurations that the bulk write sdk was uninstalled successfully.
Uninstall through double clicking the msi package and not through the "Add or remove programs option" of the Windows Start menu.

checked on Windows10 with the attached msi from MCOL-1671
uninstall failed after install, then
uninstall, install after each of the steps
1. with no Python installed
2. with Python 2.7 installed
3. with Python 2.7 and Python 3.7 installed
uninstall Python 2.7 and retry to uninstall the bulk write SDK:
fail to uninstall the bulk write SDK with only Python 3.7 installed
fail to uninstall the bulk write SDK after Python 2.7 was uninstalled
uninstall Python 3.7 too and retry to uninstall the bulk write SDK – failed

That is correct, the MSI provided in MCOL-1671 doesn't include the patch introduced in MCOL-1812.

I added a MSI with the patch to this ticket as buildbot is currently not building mcsapi's MSI packet.

checked with the new build package MariaDB ColumnStore Bulk Write SDK-1.2.1-1
note:
As workaround in addition uninstall the MSI package from Windows 10's "Add or remove programs" dialog/screen does uninstall / alter the Bulk Write SDK correctly.