Organic Groups - How to disable "Groups" Tab
I had a similar problem with OG Extras installed, the view and members tab would show even when a site visitor wasn't logged in, I wanted it hidden for non registered users or non-admin users. 

To stop it showing I edited the view 'OG Extras group members (User)' made sure I had the Page, not the block of the view selected and changed 'Access:' for the 'tab menu' to Role | administrator, this means that when logged in as an administrator I can see the desired tabs but when logged out the tabs are hidden.