MSFS 2020 v 1.31.22.0 on Windows PC
Startup always displays the Content Manager then World Update: New Zealand with the progress bar around 50%. When the bar reaches right side, it enters the Welcome screen and all is fine.
Anyway to “finish” the update once and for all?
Delete the folder that the sim hangs up on.
When you start the sim the next time all should be good.
The sim doesn’t “hang”, it just “completes” the World Update: New Zealand and all is well for that session.
Is there a way to delete the whole World Update: New Zealand and redo the update?
When the sim is up and running, go to the Content Manager and uninstall WU XII: New Zealand.
Shut down the sim, and restart it.
Reinstall the WU and see if that solves the issue.
Interesting: Started the app, Installation Mgr checking updates displayed, then World Update: New Zealand starts at 50% progressing to right side of screen, then Welcome screen. Checking Content mgr: World Update XII: New Zealand - “Not installed”, so I clicked install and it downloaded 5.92 GB and declared the download complete, so I shutdown.
Starting the app, it still showed the Installation Mgr checking for updates, displayed World Update: New Zealand at 50% progressing to 100% and then entered to Welcome. Content Mgr showed Installed 11.77GB, and I shutdown.
Starting the app, it still showed the Installation Mgr checking for updates, displayed World Update: New Zealand at 50% progressing to 100% and then entered to Welcome. Content Mgr still showed Installed, so I uninstalled it. Content mgr showed “Not Installed - Installation available”, so I shutdown.
Same as original behavior - back at starting situation: Started the app, checking updates displayed, then World Update: New Zealand starts at 50% progressing to right side of screen, then Welcome screen. Checking Content mgr: World Update XII: New Zealand - “Not installed”, so I clicked install and it downloaded 5.92 GB and declared the download complete, so I shutdown.
Starting the app, it still showed the Installation Mgr checking for updates, displayed World Update: New Zealand at 50% progressing to 100% and then entered to Welcome. Content Mgr showed Installed (17GB), and I shutdown.
How do I manually clear any downloaded “Deleted/Not installed” - NewZealand files?
It’s pretty hard, they are scattered everywhere.
I’m not sure you actually could remove them all.
One thing you might try is this:
OK - so after uninstalling and re-installing @Jimrh1993 solved the mystery updating on every load: After the installation manager checks for updates, an advertisement for whatever is the latest update is displayed while MSFS finishes loading the program. The progress bar is not for the advertised update, it is for loading MSFS and indeed when it reaches the right side, the Welcome screen soon appears.
Now the ad is showing Oceana WU XIII while MSFS finishes loading.
Thank you Jim!
MSFS has some “interesting”, (as in Chinese “interesting”), quirks - and like the Minoan maze, there is the occasional Centaur in there. People discover them all the time, (you can consider them “Easter Eggs” if you wish). So much so there is an entire forum dedicated to them. 
https://forums.flightsimulator.com/t/what-annoying-msfs-bug-flaw-still-remains-in-2023/567370 - among others
It should be noted that a “splash screen” displayed while loading is a very common Windows program behavior - even X-Plane (11 and 12) do this, but they don’t display a screen that could be confused for a request to update.