Tested on Kubuntu Cosmic Daily. This appears to be regression from the version of discover shipped with Kubuntu BB.
Created attachment 114937 [details] I need to click on Cosmic Main to see it is actually a PPA.
And then unchecking the checkbox appears to have no effect? Clicking the trashcan appears to delete that PPA. In the older version of Discover, I could click the check-box to un-enable that PPA.
> And then unchecking the checkbox appears to have no effect? Separate issue, please file another bug for this. *** This bug has been marked as a duplicate of bug 390570 ***
*** This bug has been marked as a duplicate of bug 390569 ***