You have a choice about removing the resistor or cutting the trace. Both are effective ways of 'breaking' the signal path. I opted to cut the trace because it can be repaired easily with a trace pen if you change your mind. I do not know how to solder SMD resistors back in place with a good old fashioned soldering iron.
Doug Oade had posted emphatically that you should not cut the trace. His opinion. Most of the UA-5s that get messed up by DIYers have a problem with the jumper, not the cut trace. With the jumper, the soldering work is close to some other traces and a little dribble of extra solder in the wrong place will interfere with the s/pdif output. It's pretty easy to tell because the optical light will not come on. Nothing permanent - you just have to clean up your work (don't ask...)