Some Android apps require that you sign-in using your Google account (access your private data, Google + circles, contact list, email address,...). If you no longer use these apps, here's how to unlink them from your Google+ profile.
Open Google+ app and tap on the Menu key > Settings. Scroll to Account settings and select your account:
Tap on Apps with Google+ Sign-In:
Select an app and tap on Disconnect:
Image: © Asif Islam - Shutterstock.com