I made uninstall avast from VM and found that aswArKrn driver is the only one which is present after uninstall (in stopped state). Is it expected behaviour or uninstall bug?
hey, i don’t think I’m sure, but i believe that that has occurred because of the registry, when you uninstall a program some parts of the file stay there, but again I’m not pro on this.
sincerely yours,
Bluegang6
Uninstall leftover… 
maybe Avast Uninstall tool should take care of it.
aswArKrn.sys is part of the standalone antirootkit tool, not avast itself.