Remove unused Mobile Social Facebook endpoint

common/lib/xmodule/xmodule/course_module.py

@@ -338,15 +338,6 @@ class CourseFields(object):
         help=_("Enter the unique identifier for your course's video files provided by edX."),
         scope=Scope.settings
     )
-    facebook_url = String(
-        help=_(
-            "Enter the URL for the official course Facebook group. "
-            "If you provide a URL, the mobile app includes a button that students can tap to access the group."
-        ),
-        default=None,
-        display_name=_("Facebook URL"),
-        scope=Scope.settings
-    )
     no_grade = Boolean(
         display_name=_("Course Not Graded"),
         help=_("Enter true or false. If true, the course will not be graded."),