Excluding a device from #OhmHours
You can exclude a device from #OhmHours by locating the device widget on the Devices page, and clicking the settings icon. (The gear icon at the top/left of the widget)
Once in Settings, click "Exclude from OhmHours", to exclude the device from turning off during your #OhmHours.
Removing a device from the Devices page
If you'd like to completely remove a device from your device page, you'll need to delete the device from the app you used to connect the device.
For example, to remove a TP-Link smart plug from your Devices page, you'll want to go the Kasa app, and delete the device there. Once that's done, the device will no longer appear on your Devices page.
Another example would be, for Nest thermostats, you'll want to remove the Nest from the your account on the Nest website to have the device no longer show up on your Devices page.