I was downloading Avast Free and it froze mid setup, the interface was not visible and as I tried to stop it and start anew I couldn’t get rid of the halway loaded files. Everytime I try to delete them or uninstall them I get the error that I am not authorized. What to do?
You could Uninstall and Try again. 
Run the tool and follow instructions.
Avast uninstall tool is here: https://www.avast.com/uninstall-utility
Probable cause of interruption: Stoppage of downloading while installing.
Try offline installers here: https://forum.avast.com/index.php?topic=221320.0 Scroll down for offline installer. (Hint: Save downloaded file in case you need it later.)
You’ll need the uninstaller schmidthouse provided and uninstall/run it in Safe Mode, as you can uninstall from there.
Thanks Mchain. I could have provided link to offline installer 
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