I cannot delete apps from Launchpad.

I see. I had thought that Launchpad was just a more extensive program-launching facility than the Dock. But I infer from your response that it is in fact a collection of ALL available apps that we are welcome to sort as we wish, and that therefore an app may ONLY be removed from the Launchpad by uninstalling the program, one way or another. But if this is so, then is it correct that clicking "x" on an App Store app in the Launchpad will in fact uninstall the program rather than just removing it from the Launchpad but leaving it in the Applications folder? If not, then non-App Store apps may only be removed from the Launchpad by uninstalling them while App Store ones may be removed by clicking "x" and they will not be uninstalled. If so we are back to my original question. Thanks for helping with this!

That's good to know. Actually that's a handy shortcut for uninstalling a program. I am glad I did not try to remove anything essential from the Launchpad then. Thank you again :)