It looks like you press down on it and it should pop up.  That's all I can get from the on-line documentation. See page 16 in the setup guide [URL]    
I have finally found a need for the retractable camera on my Inspiron 5477 All in one. How do I get the retractable camera to pop up out in the top of the monitor portion of the computer? Device Manager shows it is installed and working properly.Thank you.
Retractable Camera