Remove approved devices from WDS
When you approve a device in WDS you may sometimes need to restart the process and change its name etc…
Simply deleting the computer account will give an error next time you try and pxe boot. You will also need to run the following command to clear all local cached copies of approved machines from the WDS server.
WDSUTIL /delete-AutoAddDevices /devicetype:ApprovedDevices
content from: https://community.spiceworks.com/how_to/23956-remove-approved-devices-from-windows-deployment-services