Association types enable you to further identify the type of association that exists between two membership records. You are allowed to specify the type as seen from both sides, i.e., "Joe is Jane's Husband", "Jane is Joe's Wife", therefore it is good to create opposite entries.
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 Association Types
3.Modify the list as needed.
Entries on this list can be combined into one. See Merging/Combining Values for details.