Help with weird face

I am trying to make a sharp point in blender but when I do I get this weird face that shows up. Please help.
Here is what it looks like.,ddJGvSH#1

You have a concave quad. Cut the face


I don’t want to lose the face though I just want it to be a small point. If I take another side of the cube and pull it in, it doesn’t have that. It only does that with certain sides of the cube. I could easily rotate the cube and use that side that doesn’t do it, but when I am modeling and use my extruded parts I can’t just rotate it to fix it. Here is a picture with 4 cubes, I pulled each corner near the other corner, only 1 of the 4 does what I want it to, the other 3 make that concave face.

only the one on the bottom left doesn’t go concave.

Also if I deleted those faces what would I do to properly get them back and not concave?