Out Of Nick Young Fight

Blueface will not be stepping into the ring with Nick Young on Saturday -- the rapper has not yet been approved for a boxing license ... and now event promoter Austin McBroom is scrambling to find a replacement with only 3 days until fight night.

TMZ Sports is told the 25-year-old Thotiana rapper received a letter from the California State Athletic Commission on Tuesday informing him his application for a pro boxing license in the state would not be granted until he appeared before the organization in October.

Obviously, that means Blueface can't fight Swaggy P on Saturday's Social Gloves 2 card at Banc of California Stadium in L.A.

McBoom is headlining the event with rival and fellow…