Boeing Company Undifferentiated or Other Model
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (mon) 6
Distraction; Situational Awareness; Workload
ATC Issue All Types; Conflict NMAC
Air Traffic Control Issued New Clearance
Human Factors; Procedure
Aircraft X in left closed traffic to runway XX.  I gave Aircraft X traffic to follow; an E145; on final. When he reported the traffic in sight; I told him to follow that traffic and additional traffic was Aircraft Y on a 7 mile final.  I was watching helicopter traffic on runway XY.  I looked at Aircraft X and realized the sequence was not going to work.  I cancelled Aircraft X approach clearance and gave him a 050 heading to clear him of the traffic on final.  Aircraft Y called local control stating they are having a near miss with Aircraft X off their nose. I informed Aircraft Y it was Aircraft X; that was on a 050 heading and will continue on it.  I should have extended Aircraft X on the downwind to follow Aircraft Y.
A TRACON Supervisor reported an aircraft declared a NMAC with traffic the reporter had vectored off the final approach course.