Since my post of six months ago, I've probably done a dozen install/uninstall/reinstall cycles, typically LabVIEW 2016, 2017, and 2018 (all three together), and recently I've added 2019 to the mix. In all cases, these involved 32-bit LabVIEW running on 64-bit Windows 10.
In all cases, I have been successful when using the "proper" Uninstallers, namely Control Panel, Programs and Features, National Instruments Software and/or NIPM (note that NIPM came in with LabVIEW 2017 -- "pure" LabVIEW 2016 systems probably won't have it unless you are super-agressive about NI Updates). If NIPM is on your system, do not remove it until you have uninstalled every other piece of NI Software (using either NIPM itself or Control P.anel/Programs and Features). Also, remember that you use NIPM to uninstall NIPM (and you can't do it if there are other things that it "sees").
A late note -- I have discovered (and reported it to NI, who is checking that this is a "feature" of NIPM 2019) that it is possible to have a system with NIPM that can remove all NI Software but not NIPM! I found a work-around and documented it in a Service Request -- I understand NI is testing it and will file a CAR if this is, indeed, an "undesirable Feature" (typically referred to using a 3-letter term starting with "b" and ending with "g"). If anyone stumbles upon this situation, send me a PM ...
Bob Schor
