Well, it looks like the disks were never marked as ASM disks. If that is the case, then they should be fine to reuse.
The point of cleaning down the disks is to make sure they are not already marked as ASM disks, so they will be seen as candidate disks for the new installation. If they were never marked, they should be seen as candidate disks anyway.
Unfortunately, in the grid installation GUI, it showed up as "Member". This is correct as I did install once successfully. However, due to some issues, I need to reinstall the grid and have removed the grid software and start all over.
The /usr/sbin/oracleasm createdisk DATA & deletedisk worked only when I use ASMlib to present the disks. If I use Udev, apparently I can't remove them using the command "oracleasm".