It requires it being done whilst Avast isn’t active and using a special program.
Clean Reinstall:
- 1 Download the avast! Uninstall Utility, avastclear.exe Avast Removal Tool | Download Avast Clear | Avast and save it to your HDD. Make a note of the steps required or print the page.
- 2 Download the latest Avast off-line installation file for your Avast Program https://files.avast.com/iavs9x/avast_free_antivirus_setup_offline.exe and save to your HDD.
- Follow the instructions in the link in 1.
AVAST Offline Installation Files
- Free: https://files.avast.com/iavs9x/avast_free_antivirus_setup_offline.exe Or Premium: https://files.avast.com/iavs9x/avast_premier_antivirus_setup_offline.exe for Avast Premium.