Extrude/scaled to create mouth, can't move outer loop vertices w/o extruding

I’m a newb working on a head in blender using some online tutorials. After using the extrude + Rclick + scale to create the faces for the mouth, I tried to adjust the outer loop vertices. But everytime I tried grabbing the vertex, it would extrude instead. Is there something I’m missing? Does extruding/scaling lock the outer vertices into only being extruded? Any kind of help would be greatly appreciated!

I think I realized what the problem was. Somewhere along the lines I added a Subdivision surface modifier. Now I am just trying to figure out how to remove it from those specific vertices.