If the water is in the Comptip, drill two small (3/16") holes about 6" from the top on opposite sides (one is for draining, another for a vent). Once the water is out, plug the holes with silicone or a piece of duct tape. A permanent plug is a pop rivet with a sleeve.
If the water is in the lower mast section, you'll need a hole to drain it. If you have a sail feeder, remove it - that will leave two small holes for water to drain.
If you don't have a sail feeder, drill a small (3/16") hole in the mast's web at the sail cutout. A vent hole is not usually needed here, since the internal volume is much greater than the Comptip. Again, seal like you would with the Comptip.
Once the water is out, you should really find the source of the leaks.
This was very useful and although I am not sure what a sail feeder looks like, this information prompted me to look in the area where the sail is fed into the mast where I found two sheet metal screws. My guess is that the previous owner had a similar accumulation and did the drilling to eliminate the water.
T30198 in Jacksonville