The recession describes the order in which the newly-married couple and their wedding party ceremoniously exits the wedding ceremony.
The music played during the recession is known as the recessional.
Merriam-Webster Online Dictionaryrecession (noun)
the act or action of - receding withdrawal
a departing procession (as of clergy and choir at the end of a church service)
a period of reduced economic activity
the act of ceding back to a former possessor