I know that for some ad networks that URL is just for reference/info - and not really used. In fact I have apps on some ad networks that are missing this URL info (either I forgot to update it after testing etc.). But they work.
It might be an issue with some - for exanple admob etc. maybe … but even that is not relevant perhaps for these reasons:
you are ENCOURAGED to use a separate APP ID for each app (for better app-specific stats), but not required. In fact you could use the same APP ID/KEY etc. for all your apps - you would get consolidated results/stats - but there is no language suggesting that the ad network dislikes that … (maybe so on some ad network - I don’t know of any)
even on admob - the Site/App is actually NOT ALWAYS linked to a real app - in fact for some things like implementing Admob eCPM floor beta - you NEED to create a fictitious dummy Site/App - that you then link the mediation to - supposedly this is so you can track it’s stats (though practically stats are kind of flaky for that - but that is unrelated to this discussion).
Thus, it is possible that removing an app from Google Play will PROBABLY do nothing to your ad accounts.
A second question is what happens if you remove your admob Site/App for that app ? I suspect this is the same as if you enter an incorrect APP ID/KEY etc. into your app for that ad network - the ad network SDK will perhaps output an error message to logcat - but I don’t think it will show anything on screen (ad will not be delivered and so for admob etc. it is likely that no ad will appear).
So practically I suspect removing an app from Google Play or from admob etc. would do nothing drastic - the app would continue to function for those users who are still using that app.
I’ve just unpublished two of my apps from Google Play - they were featuring various cartoons and since Google was lately after these kind of apps, I didn’t want to take a chance.
I have the same question as the original poster - should I disable AdMob for these apps? I haven’t seen anything about this in their TOS. And, as a matter of fact, I don’t even see an option in AdMob to stop displaying ads.
OK, I’ve just realized how to delete ads - you got to Sites & Apps -> Manage Settings -> Edit -> Delete Site. That’s it. I’ve done this, and I think it won’t affect the apps at all - no ads will be shown and that’s it.