I have a bunch of iphone apps inside Itunes, one of them automatically tries to install itself whenever I remove it from the phone. (Its button in the App itunes list shows "Installing") If try to delete it from itunes using this method, the delete button just doesn't do anything. How to remove an app from Itunes 12.2.x ?
Followed @lax solution: clicked the iTunes Apps tab (not in the "iPhone" tab!) there I could select and delete the apps.
I'd say, close iTunes, go to your iTunes Media folder and open the Mobile Application folder inside.
Then simply delete the IPA file of the app you wish deleted.
Finally, run iTunes and you won't see the app listed anymore.