Should I remove my left lateral incisor? (Photo)

In NO way would removing the left lateral be a good idea. If symmetry is a goal, bonding composite or a porcelain veneer can be the answer.  Ideally braces first to align better, then decide on any restorative options, but removing is a TERRIBLE idea.

A talon cusp on the lingual (back) of the tooth makes the tooth very thick.  The thickness prevents the tooth from moving back to correct the Protrusion.  Since all of the front teeth have to line up for a nice smile, you can only move them as far as the talon cusp tooth can move.  Trying to make the tooth thinner often results in needing a root canal.  If your treatment plan requires other extractions, it would make sense to remove the talon cusp tooth (instead of a perfectly shaped tooth somewhere else) .  In fact, I would say that you seem to have a very thoughtful orthodontist who is thinking about all options.  It would not effect your jaw in any way. If you were really concerned, a root canal specialist could evaluate the talon cusp tooth to see how close the nerve was to the back of the tooth and whether or not it could be thinned enough with out needing a root canal.   Discuss it further with your orthodontist if you still have concerns. Sorry that there is not a more straight forward answer.  Talon cusps are always difficult to deal with, not because it is a serious health issue, but because the are always on upper front teeth and can really mess up the smile esthestics because of their thickness if they are not dealt with.