Click "Security Group" from the left pane
Select the appropriate security group
Click "Delete Security Group" in the upper right
Click "Delete" in the displayed popup
Confirm that it has been deleted
Click "Key Pair" from the left pane
Select the appropriate key pair from the list of key pairs displayed in the main column.
Select "Action"-> "Delete" in the upper right
Enter delete in the field and click the "Delete" button
Confirm that it has been deleted from the "Key Pair" list and exit
Thank you for your hard work!