Why this is even an issue is a little beyond me. It must come up often enough to get others annoyed by it. You have some piece of software that is crashing your system sufficiently that you are unable to remove it using a regular boot. So, you boot into Safe Mode. Only problem is, the installer service is disabled during Safe Mode.
Well, let’s hack the registry a bit and sort that shit.
(Don’t be scared, but do proceed with caution and at your own risk.)
So log into your Windows 10 (or whichever, this ought to work even as far back as, ugh, XP) in Safe Mode (f8 is often useful to get there). Once you get in you can open the Registry Editor from a command prompt. Holding down the Windows key and pressing R (Win-R) will open the run dialog; then just type regedit and hit Enter.
Once in the Registry Editor navigate to HKEY_LOCAL_MACHINE—> SYSTEM—> CurrentControlSet—> Control—> SafeBoot—> Minimal and right-click on Minimal. From the local menu which pops up, you’ll want to choose New —> Key. Name this new key MSIService.
(I have seen one report where the name MSIService did not work and the user used MSIServer instead. Try MSIService first and go from there.)
Within the new key, MSIService, right-click on the item called Default and choose Modify from the local menu which pops up; then in the Edit String dialog set “Value data:” to Service. Click the OK button.
Ok, that gives the system what it needs to be able to run the Windows Installer service during Safe Mode.
(Note: if you are running Safe Mode with networking, you want will to do this same work also under HKEY_LOCAL_MACHINE —> SYSTEM —> CurrentControlSet —> Control —> SafeBoot —> Network, but I haven’t test that.)
Now let’s start that service so you can run your uninstaller (or installer for that matter).
In an Explorer (file browser) window, navigate to This PC (or Computer or My Computer) —> Local Disk (your disk, probably C:) —> Windows —> SysWOW64 (earlier systems it may be in System32) —> services.msc; then right-click on services.msc and choose “Run as administrator” from the local menu which pops up.
Now locate the Windows Installer service in Services, right-click on that, and choose Start from the local menu which pops up.
That’s it. Go forth and uninstall.