Maintaining Circles (moving, adding, deleting people) is simple. Click on the Circles logo as shown in the following screenshots and you'll have access to everyone in all your Circles. I'm up to 1288 people now, which means I have a lot of sorting out to do.

To drill down to just one circle, such as my Friends circle below, click on the name of the circle (in its blue circle at the bottom of the page), and we get a pop-up dialog box as follows:

While the preceding procedure is okay for quick operations, such as adding a new person, it is more of a launch pad than an end point for circle maintenance. Let's look at the bottom line of the box:

Over to the right is the Cancel button (stops the operation, closes the box) and Save (saves your changes such as the new friend added, and so on).

Now back to the three links on the bottom left: