Trying to lighten stained cabinets

First..... that is why any stain should be "tested" in an out of view spot first to see what it looks like, before applying to any front surface.

But now ... maybe try some paint remover [in that out of view spot] to see if that helps. I DON'T KNOW IT THIS WILL WORK. Some paint remover work better than others. I would check at a place like Sherman-Williams for a paint remover.

Sanding the wood might lighten the color, but I am not sure about your alder wood and how porous it is.

Rag and mineral spirits/turpentine. Steel wool and water an option also, but make sure you go with the grain. Neither option is easy.