Depending on what your policy is, ultimately only physical destruction is considered secure. Given the state of recovery methods available today.
If they are in the same group, you'll need to remove all the volumes, then remove one member. This will reset it.
Then at the CLI of the remaining member run 'reset' command.
Now you have two individual arrays. I would connect to them one at a time and create a NEW group. With just that one member. Create a RAIDset then reset it again. Do the same to the other.
If the two members were in the same pool, then data was split between. So recovery at this point would be extremely difficult by wiping out all the block maps.
Also EQL FW 10.0.x firmware added a more secure reset option. It will do a more intense erasure process.
However, that's not to be confused with the old, now unused, DoD secure erasure.
We appreciate your input here. We will move forward with your recommendations for the decommission.
Thanks so much for the advice.