Dashboard has a clear button that would clear all discoveries, but it is not shown:
</thead>
<tbody data-ng-if="convertTo.saved || !discoveredDevices.length">
<tr data-ng-if="convertTo.saved">
<td class="col-11">
<i class="p-icon--success">Success:</i> {$ convertTo.hostname $} has been add to {$ site $}.
<a href="#/machine/{$ convertTo.parent $}" data-ng-if="convertTo.parent">Go to the machine devices page.</a>
<a href="#/devices" data-ng-if="!convertTo.parent">Go to the device listing.</a>
</div>
############## CLEAR BUTTON
<td class="col-1">
<button class="p-button--neutral" data-ng-click="convertTo.saved = false">Clear</button>
</td>
############## CLEAR BUTTON
</tr>
<tr data-ng-if="!discoveredDevices.length">
<td class="col-12">
No new discoveries
</td>
</tr>
</tbody>
This clear button is different. It's just for clearing the notification that tells you that you can see the newly-added device on the machine details screen (when you add a discovery as a container).
The button to clear all discoveries was discussed but not ever designed and implemented.