I found the process I had used previously. Here it is here. Summarized below.

Make sure the VM in question is shutdown.
From the console xe vm-shutdown uuid=<UUID of Your VM> xe vbd-list vm-uuid=<UUID of Your VM> params=uuid,type xe vbd-destroy uuid=<UUID of Your CD/DVD> Of critical importance do not select Disk, ensure you select the UUID of the cd Repeat step 4 as many times as you have CD's that are unusable. Reboot the VM and add the device again.

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