Just an FYI, but the reason the headrests are difficult to remove is to avoid them becoming a projectile during a frontal collision. One of the two headrest guide posts (the two metal rods) is designed with a notch that engages with the headrest guides (the plastic piece) that prevents easy headrest removal. Basically, it's a fail safe from an occupant completely removing a headrest or raising it beyond its intended (safe) range of motion. Only one of these headrest guide posts has this notch, so altering the position of the headrest by rotating it 180 degrees does not guarantee that the headrest will not dislodge during a collision.
For those of you who still would like to remove and reinstall the headrests in a different orientation, you can do so.
To remove the headrests, simply straighten the outermost end of a paperclip, raise the headrest to its uppermost position, insert the paperclip into the small hole on the plastic headrest guide, and press firmly while pulling upwards on the headrest.