City suffered an early scare at SportCity, with Albion striker Rob Elvins heading home after six minuutes, but within minutes Shaleum Logan converted from close range after good work between Ishmael Miller and Ashley Grimes.
Miller, this season’s top scorer at Academy level, then put City in the lead from a Grimes free-kick, before Onuoha claimed his goal with a 27th-minute header.
Grimes had a penalty saved in the second half, though the City kids still managed to make it four when Logan headed his second from a Kelvin Etuhu cross in the closing stages.
City: Schmeichel, Wallwork, Williamson, Richards (Russell 87), Onuoha, Williams, Etuhu, Johnson, Grimes (Sturridge 87), Miller, S Logan.
Subs: Matthewson (GK), McGinlay, Marshall.
Attendance: 501.