They are all in system restore and Avast does not delete them as it breaks the restore points
The easiest way is to clear the restore points
Clear Restore PointsGo
Start > All Programmes > Accessories > System tools Right click
Disc Cleanup and select
run as administratorWhen it pops up at the first prompt select OK after it has done some calculations the tabs will appear
Select
More Options tab
Press Sytem Restore and Shadow Copies
Cleanup button