I have an unused bar sink and I want to remove the sink and need to know how to seal the drain-pipe under the counter. I don't want to remove it in case I ever want to re-use the drain.

There should be a stub out where the "P" trap goes through the wall. If the house is very old you may have an "s" trap through the floor-this is no longer allowed in new construction. Remove the sink and drain line, put a rag in the hole and then take the pipe to HD or Lowe's and get a short piece of PVC pipe that has the same OD. Cement a PVC cap on the short pipe , cut the pipe so it will stick out of the wall an inch or so, remove the rag, push the pipe into the wall and tighten the nut on the stub out fitting. That will seal the drain from leaking sewer gas and can be easily removed if need be. Good Luck.

If pipe is PVC u can glue a cap on end. If sink is wanted in future, cut off cap. May have to extend stub out.

Chuck

Tell us what material the stub out is and we'll tell you how to cap it off.
We could use more details. For instance, will the stub-out be OK outside the wall or do you wish it hidden? And what about the water pipes? Back to you, Tom

The stub is pvc and I want to leave the stub exposed outside the wall as it is under a cabinet. I am taking out the sink and leaving the water lines at the turn-off valves under the counter. Just want to cap the PVC drain to close off sewer gas and have it available to reconnect if needed in the future

Most likely a 1 1/2" pipe coming out of your wall. (check to be sure). Ask for a 1 1/2" PVC permanent cap plus a small can of PVC Cement and PVC primer,
Good luck. Tom

Thanks for the quick response and help--much appreciated