I have 4 gmail accounts in my phone but when I go to Google play it is trying to use an obsolete account and in Google play there is no drop down box to choose an active account. (Google play was using one of my active gmail accounts but it all of a sudden stopped working and went back to the inactive gmail account. I also cannot delete the obsolete account off my phone because in settings/account preferences it says in gray "not all settings are available" and there is nothing to click. I was trying to delete it so google play would not try and use it for signing into google play)
Open play store and slide from left to right then you can see a drop-down list in the navigation pane. There you can choose the account.
Google play store is inter connected with the Google+ app in your mobile. If you want to remove an account in play store, you can do it by removing that account at google+ app in your mobile. It won't delete your account.