if you grasp the stem of that leaf right where it joins the main stem and pull down it should just snap off right at the joint.
...once you remove it take it out and flip it over and examine it very closely for pests, if you don't see any then just keep an eye on things and look for others.
...btw, it looks like the plant is hungry, can't tell for sure because your pic only really shows that one leaf but i see some light green leaves in the pic and that could indicate hunger.
peace, bozo
...oh yeah, pulling that one leaf off won't hurt anything.