Can't uninstall a program

I "upgraded" to W11, installed a program which does not work in W11 so I reverted to W10 before uninstalling said program.  Now I can't uninstall the program and when I try to reinstall it, the installshield thinks I want to uninstall it.  It is pointing to the installer program (.msi) but doesn't recognize it eventhough it is the exact name that it is looking for to un