You can easily remove a failed node using the Zensys Tool which can be found here to download it: https://aeotec.freshdesk.com/helpdesk/attachments/6091420613
Marking a device "is failed" requirement
Check the topology of your devices, if there is any association or route that the device you are trying to remove is a part of, this will cause the "is failed" operation to fail.
If there is a neighbor node associated to the device, go to each of the devices and update the neighbor nodes around the device you are trying to remove.
Always Listening Nodes (Plugin / In-Wall applications)
Skip step 4 in the below steps if you are removing a no longer working always-listening device. Step 4 will only apply for battery devices only.
Removing Failed Node
1) Open up Zensys Tool
2) Connect your Z-Stick under "Categories -> Port"
3) Highlight the failed node by clicking on it
4) Under Queue Override, click on the box, and a check should appear
5) Send a NOP (No Operation) [Note, if it fails, continue to go through the steps anyways]
6) Check to see if the Node has failed, at the bottom of your logs page, it should say "Node is failed..." [Note, if it fails and does not say this, continue to go through the steps anyways]
7) At the toolbar on the very right, look for the "Remove Failed" button and click on it.
8) Now close Zensys Tool and open it back up and re-connect your Z-Stick. The failed node should have disappeared.