Uninstalling fluxMotor problem

I downloaded fluxMotor 2020, didn't use it and now I try to delete and I can't.

I tried to uninstall from control panel, after the message "Do you want to allow this app to make changes... uninstall" and pressing ok nothing happens.

I have found the Altair folder in program files, tried the uninstall app - after the massage above nothing happens. 

I tried to delete the whole folder but it says it's open somewhere else and it can't be deleted (it's not open).

Between each of these steps I restarted the computer.

Please give me a detailed guide of how to uninstall this program (I have windows 10 home version 2004).