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How would I go about doing that?

Edit: Do you mean:

dam_2.jpg

I would like to know as well!!! Using a lens correction?

I prefer how you've cropped the small bit of red out of the bottom of the left hand side. (Y) Definitely this version!

Lightroom can do that for you based on your camera and lens profile. Look under Develop > Lens Correction. Occasionally, this will be done automatically.