uninstall avast

Hello,
so here is the story : somehow avast did installed on my computer during installation of something else (Nasty !)
but now, i cannot it uninstall :

  • there is not listed in the software in windows uninstall software window
  • i cannot kill avast tasks in the task manager
  • i cannot kill avast tasks in CMD line
  • i cannot disable autorun avast tasks for startup in task manager
  • there is avast folder in my program files folder

which way i may to process normal uninstallation ?

windows 10 64-bit system

Follow instructions: https://www.avast.com/uninstall-utility