How to Update Avast Antivirus Manually

Avast snuck onto my computer 2 days ago without permission and gave itself higher permissions than exist which has made it so far impossible to delete/uninstall/quarantine/rename/move. So far the only advice I can find to get this Virus off my computer is trust the company that made the virus put Another program on my computer to take it off... NO. I didn't ask for you I didn't want you and I sure as hell am NOT giving you another chance to infect my computer and steal my financial information.

I will wipe my entire computer before I risk this fraudulent company with their virus programs to steal my information or ransom my computer.