take 'em out, and bung the holes up... it's good to see nice clean lines on a single speed, if you wind a thin screw a little way into the fluted end, they will just pull out easily.
plus they're easy to get back in, like others have said, magnet and a cable, or hoover and a thread
I am running a Rascal as my only single speed and it's great. Super light too! I have replaced the cable liners before using a piece of welding wire with a slight curve in it. Was very easy.