References are used on membership records to record the way in which someone came to know about your organization. Typical entries might be, "friend", "online", "event", etc.
Note: You cannot delete a record that is in use. One solution is to create an entry called, "Undefined" or "Unknown" and merge the unwanted entries into that one.
1.On the Home ribbon, choose Lists from the Settings section.
2.On the System Lists window, choose References.
3.Modify the list as needed.
Entries on this list can be combined into one. See Merging/Combining Values for details.