No, you do not HAVE to remove the rear sway bar. If you do, you will have more up and down movement of the rear axle which is why people like to remove the sway bar. It's also said that the rear sway bar is a bad design and can slap your rear shock causing damage. If you don't off road I'd keep it on. My reasoning for keeping it on is that in case of a roll over I'd be worried as to what an insurance adjuster may say if there is no sway bar. So it is your call as to wether or not you'd prefer to keep the sway bar on or not.