I remove the guard from most of my reels, unless we are talking little spinning reels.
I have an ultegra and I haven't actually removed the guard from this reel...no reason other than its expensive and I could sell it on. Also the guard is good on the Ultegra and works well, unlike say the Penn affinity / SurfB where it is big. clunky and prone to reset I found.
I wouldn't hesitate though - is there a reason why you don't want to do it?