Is there any NI Software installed on your computer? If you go to Control Panel, do you see (under Programs and Features) entries for National Instruments Software and/or NI Package Manager? It would be very helpful to know this before giving you advice.
Note that NIPM 2019 is, in some ways, a "new" Product, one that certainly is different from NIPM 2017 and 2018. I've had a lot of "practice" installing and uninstalling LabVIEW (typically 2016 through 2019) since NIWeek (I finished my, I hope, final install the day before yesterday) and there are definitely some interesting pitfalls ...
To answer your response Bob, there wasn't anything listed in the ControI Panel. To do the uninstall I used the NI Package Manager and selected everything and hit remove.
I was able to figure out how to get around this error on my own though (seems to be working so far at least but installer isn't completely finished), apparently the Package Manager didn't do a very good job cleaning up the registry so I had to manually delete the MIFSystemUtility key which had an old path in it.
On two Windows 10 PCs of mine, I also tried to "manually remove" stuff that seemed left over after trying to "Remove all NI Software" (I had LabVIEW 16 and 17 installed at that time). In both cases, I mucked around with the Registry, removing things that referred to NI Software. In both cases, I rendered both PCs unable to install LabVIEW, and only cured it by backing up everything, wiping the C: drive, re-installing Windows 10 (and its updates), reinstalling all of my other software, restoring my other files, and then re-installing LabVIEW. I've stopped trying to out-smart the NI Installers (and have done about a dozen or two complete LabVIEW removals and reinstalls on a half-dozen Windows 10 systems, typically LabVIEW 2016, 2017, and 2018, including a few installs of LabVIEW 2019) since.