In the Device Management section of the dashboard, open the
Installs page. Here you will see all the devices (attendants, copilots, and cameras) that are now or have been allocated to your school system.
In the Filter By field at the top of the page, enter the ATD number of the device to deallocate.
Click on the circle of the entry you have found. This selects the device and opens a panel on the right side of the screen.
In the right hand panel, find the red button labeled "Uninstall from" followed by a bus number or name. Confirm that the number or name is the bus you intend to deallocate the device from, then press it.
Troubleshooting
If you do not see the device you are looking for, the most likely reason is that you have the filters on that page set to exclude what you are looking for. Set the filters to the most inclusive, as shown in the screenshot below: for device types, select all three types, and for install state, select all:
If you do not see those filters, then you likely have the filter panel collapsed. In that case, click on the downward arrow shown in the screenshot below, which will reveal the filter panel: