Is there a way to configure whitelisted websites via terminal?
First, convert the com.apple.familycontrols.contentfilter.plist to xml. 

 sudo plutil -convert xml1 /Library/Managed\ Perferences/yourUsername/com.apple.familcontrols.contentfilter.plist


Then, edit the xml file and remove the site that you want to remove

sudo nano /Library/Managed\ Perferences/yourUsername/com.apple.familcontrols.contentfilter.plist


This should help you.