Exclusion isn’t about removing a zwave device from your ST account. It’s about removing network ID information stored in the end device that might be preventing it from being added to a new network. Any new network. That’s why Z wave exclusion is usually the first troubleshooting step when you are having difficulty adding a new zwave device.
Zwave is unusual in that most other protocols give each device a unique device ID which is assigned at the time of manufacture. Zwave instead has the hub for a new network give each device its network ID at the time that it joins. So when you first add a device to a Z wave network, it gets two pieces of information: the hub’s ID and its own ID on that hub’s network. It stores this information in its own firmware. Until those two fields are cleared, the device will refuse to join any other hub’s network.
There are pluses and minuses to this approach, but it just is the way the independent third-party zwave standard decided to handle joining a new network.
Of course, they understood that you might not have the original hub anymore. The hub itself might have been damaged, you might have bought the end device used, sometimes it’s even that a brand new end device was connected to a test network at the factory and they didn’t clear the information properly before shipping it out.
So the specification allows ANY Z wave hub to issue a “general exclusion“ command, which can be heard by any nearby Z wave device. That device will then only act on the exclusion command. The device doesn’t ever have to have been connected to that hub’s network. So you have to do something to tell it to accept the instruction to clear the old information, usually a very specific tap pattern. You can’t just guess at what it is, you have to look it up in the user manual. And usually you only have about 30 seconds or so to do the tap pattern at the time that the hub is broadcasting the general exclusion.
You still haven’t mentioned the model number for the specific plug which is giving you difficulty. (The Tap pattern can be different on different models even from the same manufacturer.)
If it does happen to be the MP22Z model, there is a “programming button” on the top of the case. You issue a general exclusion from the smartthings hub and then you have to quickly triple press the programming button. You should see the LED on the plug start blinking rapidly. At that point, the exclusion command should be accepted.
So there is both a required action (triple press the button) and a required sequence. (use the smartthings app to issue the general exclusion, then quickly do the triple press on the plug and you should then see the plug’s LED start blinking rapidly).
After the exclusion is complete, then you just go through the normal ad process of adding a new device.
Here’s the user manual for the model that I mentioned:
Again, this is very typical of a Z wave device, nothing specific to smartThings.