Google have begun messaging developers/publishers of apps that as part of their Google+ shutdown, any app which contains Google+ functionality needs to be updated in the next month or so in order to remove this Google+ integration, otherwise the app will be suspended on the Play store.
Whilst we of course are updating the current Google Play Services extension on the Marketplace with this same change (plus other fixes) and would recommend that you just use that, if you have an app you need to maintain where you just want to make as small a change made as possible and get the apk off to Google, updating all your Google extensions and potentially GMS2 and Android SDK components to match and then re-testing everything might not be practical.
This guide will show you how to quickly edit your current extension in order to remove the small integration with Google+.
Please note that the only time Google+ was being referred-to (at least, in any extension for quite a while - super-old extensions may vary, so test well) was when logging-in for Google Cloud Saving access. If your project uses cloud saving, we would advise you to test carefully that saving and loading still work after making this change - you might need to get the updated extension off the Marketplace.
How to Edit the Files
Open your project in GameMaker.
1. Double-click the extension to open its properties.
2. Double-click "Android" to open the extension's Android properties.
3. Remove the entire line shown below for plus:11.8.0 (and the blank line this creates).
So then it ends up like:
4. Close the extension editor now.
5. Right-click the extension in the resource tree and choose "Open in Explorer".
6. In the Explorer/Finder window which opens, select the "AndroidSource" folder, then the "Java" folder, and open the "GooglePlayServicesExtension.java" file in a text editor.
7. Remove the entire of line 82, which says "import com.google.android.gms.plus.Plus;" :
8. On line 184, remove the ", Plus.SCOPE_PLUS_LOGIN" bit from this line, so it just reads “optionsBuilder.requestScopes(Drive.SCOPE_APPFOLDER);”
9. Close and save the text file.
And that's it. Back in GMS2, you should now clean your project cache if you have built this project recently, and then build it for Android again.
As mentioned above, we would always recommend thoroughly testing the game, but this is particularly important if you do use Google's cloud saving in your game.