evicting tenants with 2 names on lease

[Brandon P.]

Both the boyfriend and girlfriend have their name on the lease(which i see was a mistake).  They got into a fight, no longer get along, and are now for the first time late on rent. Only one of them is working, and claims to no longer want her their.  Is their a way i can get the non working tenant to leave and keep the other? If not: do i need to serve them both a 5 day notice or just give the notice to either one of them?