Vertical bulge (in shape of surgical cannula) above my belly button & how can it be fixed? (Photos)

It's hard to say what would cause the vertical bulge that's demonstrated in your photos. It's unlikely that it is directly related to instrumentation from your c-section. It could possible a contour irregularity comprised of fat or maybe scar tissue. I encourage you to visit with a board certified plastic surgeon near you for an evaluation.

There wouldn't be a cannula or any other instrument used in the upper abdomen with a C-section. If it isn't a diastasis then it is just an irregularity of the subcutaneous fat. See a plastic surgeon for options.