To uninstall a state.  Close the ProSeries program.

Win 10  

Right click the Start button > Settings > Apps   scroll down the list to ProSeries 2018, click Uninstall It will act like its going to uninstall the whole program, don't panic, it wont!   Another window opens with a list of parts to uninstall, choose IL.  Then open the program back up and choose Select and Download New Products, make sure IL is checked, then run the update, that should bring IL back as a fresh install.

Win7 

Is Control Panel > Add/Remove Programs then the same steps above