You can remove Avast from your device by following these steps:
Go to your settings and open the programs or software app. To do this on Windows, click the Windows icon in the bottom left corner of your screen, then click the cogwheel, and then “Apps.”
Look for Avast Antivirus on the list and click “Uninstall.”
Click “Uninstall” again when the confirmation pop-up appears.
Follow the steps to confirm once again that you want to uninstall the program.
The uninstallation process may take a few minutes. If this doesn’t work, you could also try to use Avast Clear — this is Avast’s uninstall utility.