The device is registered to another tenant.

This requires manual deregistration by Microsoft. (Dell cannot perform the deregistration on the Customer's behalf.)

Submit a trouble ticket in Intune.

Navigate to the Intune admin center: https://intune.microsoft.com This hyperlink is taking you to a website outside of Dell Technologies.
Go to Troubleshooting + support -> Help and support.
Click Intune.
Under How can we help copy/paste Autopilot - ZtdDeviceAssignedToOtherTenant and click the arrow, then click Contact support.
Click New Service request.
Fill out the form and attach a copy of the invoice for the computer (Microsoft does ask for proof of ownership and only accepts the original invoice).
Click Contact Me.
You see confirmation for the service request, and a Microsoft engineer contacts you. The SLA depends on your support agreement with Microsoft.
You can submit multiple devices under the same incident.