I decided to move the house to ecobee so I need to get rid of my old zwave/nest thermostats – can you do that or is there a way through the site or panel?
Looks like the Nest device is already deleted. Z-wave devices should be removed at the panel. On the Qolsys panel go into the Z-wave devices menu and select “Clear Device” While the panel is waiting to hear a device, perform the pair procedure on the tstat you want to remove.
That will clear it from the panel and from Alarm.com.