I always have 2 versions running (current and prior). The reason to uninstall later is that you might forget to export some settings like "Work Environment" before removing the version and you might lose those settings. Also if something goes wrong with the new one you can fall back to the previous one.
My procedure is install New, check it is running and after a few days uninstall the oldest one.
eduardo rolón AIA NCARB Another of the forum moderators. Macbook Pro 2.4 i9 32GB ram OS X 10.XX latest AC25 US/INT -> AC08
If you need the disk space then un-install the old version once you are sure you no longer need them.
If disk space is not a problem then there is no need to un-install at all.
I have every version from 15, plus various builds for some versions and also a couple of different national version.
They all work fine and don't interfere with each other.
If you like to double click on a PLN file to open it, generally the last version installed will be the default software.
But you can set in your operating system which program will be used to open a PLN file by default.
One of the forum moderators. Versions 6.5 to 25 Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10 Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10