Try soaking in oxiclean. It's a peroxide bleach which is gentler on fabrics than chlorine bleaches.
I use the hydrogen powdered bleach from the Dollar Tree, it is the equivalent of Oxyclean. Make a concentrated solution in the sink or the washer and then add the sweatshirt, let it soak. Then launder as usual. Best to you.
Thanks,I’ll try your ideasJoe
Soak with Oxiclean and hot water overnight. Change the water and soak again if not all out.
Make a paste of bicarb and vinegar and Let it sit for awhile then wash.