If the NavStation sw is not getting uninstalled by normal procedure, please try to download and run the Microsoft install and uninstall troubleshooter from the below link:
https://navstorage.navtor.com/software/MicrosoftProgram_Install_and_Uninstall.meta.diagcab
When starting the program, select that you have problems uninstalling a program and when you get the list of installed programs, choose NavSTation SW and proceed with the uninstall wizard. If the wizard successfully completes, reboot the PC.
Then try to install NavStation again