leave for dead

verb2

1. •
   To abandon a person or other living creature that is injured or otherwise incapacitated, assuming that the death of the one abandoned will soon follow.

   • He stood in the middle of a narrow part of the road, stopped the horse, and struck Fyot with a heavy cudgel, leaving him for dead in the ditch. — 1835
2. •
   (figurative) To disregard or bypass as unimportant.