In the Edit mode of a contact record, each association class (contacts, organizations, or venues) provides two form sections. The first form section of each class gives a list of members of that class already associated with this person with a checkbox (labeled Dis for disassociate). If you click on that checkbox and hit the button Disassociate Checked in the top form section, the association (not the item, only the relationship of it to that person) is removed. The second form section, provides a picklist of the entities of that class (e.g. the names of dance places in the class of venues) and your experience or role to that entity. By selecting from the available picklists and clicking on the Associate button it will create a relationship with that specific entity to that person.