This is really only useful in if the app you need updated is already in your Apple ID account.

Please note that the app will still work as intended.

Delete the “receipt” file (you may need to enter a local administrator username and password).

Go into the “Contents” folder, then into the “_MASReceipt” folder.

Right click the app then click “Show Package Contents”.

Go to the app listed in the App Store as needing an update (usually in the /Applications folder).

Please note that it is impossible to test this with every app in the App Store but I haven’t seen anything to say that this isn’t the way it works for all apps. Removing the grayed out Apple ID email is as simple as following these quick few steps. You can always download/update apps that are listed under the account you are signed into the App Store with, because, well you know. Situation B: you do own it and the App store allows you to download the latest version in full. Situation A: you do not own that app (it is not listed as a purchase on your Apple account). If you remove the Apple ID and enter your Apple ID then one of two things will happen. We can get rid of this however you must note that by doing the following you WILL NOT ATTAIN OWNERSHIP of these apps. If there is anything attained from the App Store (aside from system updates) then that app is tied to that Apple ID, hence the requirement to sign in as that account to perform a measly update. What does that “Update All” button do? Well your machine then attempts to update everything including any and all purchased apps. (Operating System upgrades do require one.) It may seem like this is not the case but really what you are doing is hitting the “Update All” button in the App Store. Operating System updates do not require an Apple ID. It’s because you are trying to update software that was downloaded using another Apple ID. Because it is grayed out you cannot remove it. You try to update some software on a Mac and BAM you have a pre-populated Apple ID in the login prompt.

Purify app greyed out on my iphone