You should be able to uninstall that element:
Control Panel > Programs and Features > select avast! antivirus - click the Uninstall/Change button (or right click avast! antivirus select Uninstall/Change). From the new window, select the Change option, you should now have a list of all avast elements, uncheck the Safe Zone and OK your way out. You may need to reboot to have the changes take effect.