Here is what I did to complete the install:

1. Find a .nbi folder under C:\Users\folder. This folder has .nbi folder under it
2. Open a command prompt and Go to NetBeans folder which has uninstall.exe
3. Run this command in the command prompt:.\uninstall.exe --userdir c:\Users\folder\\.nbi

folder is the folder you found in step 1.

This uninstalled for me. Hope it helps you.