How do I make Bombable walls?

Go to Data_Secret Combos and go to "bomb".Click the box by the it and
choose a Cave Walk Up or Cave Walk Down Combo.(be sure all this is on the
screen you want😉 )Then select a flag that says "bomb"and place it where
you want.😊

Just to add in, the cave walk up or down is a tile warp so that's how you can set it up to either screen 80 for the basic zelda 1 cave or to any other screen for a custom house, cave, etc. Use the blue square to show the exit position on the overworld. Putting it directly next to the cave entrance on the ground will cause the walking out animation.