Genesis 6:1-22 ASV, Genesis 7:1-24 ASV, Genesis 8:1-22 ASV and Genesis 9:1-17 ASV

http://aaronzehr.blogspot.com/2010/03/failed-attempt-1-to-remove-sin.html
The purpose of the flood was not to completely remove sin from the world. What then was the purpose of killing all but 8 people and 2 of each animal?