This was so annoying, I'm writing this to help other people. Facebook management is a labyrinth. Here's how you find the settings to add and remove people as managers from your Facebook page in the new Facebook Page Management. In short you have to
Login to facebook
Switch to the profile of the page you whose access you want to change
Go to the Professional Dashboard
Click on Page Access on the Left Side
Video for how to Add and Remove Managers from Your Facebook Page