Nick Cannon isn't fretting about his decision to walk away from $4.5 mil a year as the host of "America's Got Talent" ... because his head was never really in TV.

We got Nick at a high school in the Bronx with members of NYC's Black Lives Matter ... a much bigger priority for him than the boob tube.

As for who should replace him on 'AGT,' ... why the white Nick Cannon, of course.

RYAN'S GOT TALENT
TMZ.com
RYAN'S GOT TALENT
TMZ.com