Google rolled out the ability to manage pages in the Google+ app quite a while ago, but the user experience is so bad that it took me quite a while to figure out how to do it. Once I figured it out though, I also figured out how to mange other Google+ profiles.
To manage your Google+ pages, or other profiles, you first must sign out of the Google+ app. To do this, click the hamburger menu to open up the sidebar, then click on the gear, icon and then scroll down to Sign Out.
By signing out, you’re really not signing out. As soon as you hit the Get Started button you’ll be taken to the profile screen where you can add more Google accounts or choose an existing account.
Once you choose an account you’ll be able to choose the account holder, or one of the pages they manage.
I really don’t understand this workflow on iOS. Why doesn’t Google add a switch accounts option instead of asking you to sign out? Especially since Sign Out doesn’t sign the user out!
Oddly enough on Android it makes a lot more sense. Android has a drop down in the profile sidebar where you can select a different profile or page. Now that’s user friendly!
Hopefully that workflow comes to iOS some day, but for now, you have to follow the janky user flow as outlined above.