Remove old http Map Server references in Web App

[GrahamStobie1]

Hi

I'm going through the process of updating / removing http references in my maps and apps, but have come across a series of apps where the web app template has references to a series of http MapServer layers which are no longer present in the map (and on a server which no longer exists), so cannot be removed - does anyone know how I can get rid of them so they won't cause a problem when we switch to https only? The references show as below in the web app template.

Thanks for your help!