We do this process all the time because the new systems come from Netapp with ADP configured on encryption capable disks.
Record which disks are owned by each node in the chassis.
Bring controllers down to maintenance mode and then run "disk encrypt sanitize -all" on each node.
When that is done, do a "disk unfail disk.id" for each disk assigned to node A & B.
Then a disk assign to assign disks back to their respective controllers.
Halt the controllers, do a boot_ontap and go into special boot menu and select option 4.
Forgot to mention that when at the loader prompt run printenv and if "root-uses-shared-disks?" is not listed then run "setenv root-uses-shared-disks? false".
Then do a "seveenv" to save the setting. This needs to be done before "disk encrypt sanitize -all" is run in maintenance mode.