After making a web-map I used some data that I don't want to be displayed in the final Dashboard (as I made tile cache layers for them). I want to use their statistics but for them not to be included in the layer list on the Dashboard.
I have used the remove from Legend - so it doesn't appear in the Dashboard but I don't want it in the layer list.
Is there a way to have these layers only in the background of the Operations Dashboard? And remove them from the Layer List? (see picture - I want these removed)
Unfortunately it does not look like this is currently possible through the layer list in ArcGIS Dashboards.
You could turn off all layer visibility by opening the configuration settings for your map element and disabling Layer Visibility under the Settings tab.
One other potential option would be to create a Web Appbulider app from your web map (you can show/hide the layers in the layer list widget here) and then embed that app into your dashboard. However, you would likely need to reconfigure the other elements in your dashboard if the map element is removed.
I highly recommend that you post an idea on the ArcGIS Ideas page to have this functionality added!