unstop

verb (used with object), un·stopped, un·stop·ping.

1. to remove the stopper from: to unstop a bottle.
2. to free from any obstruction; open: to unstop a sewer.
3. to draw out the stops of (an organ).

verb -stops, -stopping or -stopped (tr)

1. to remove the stop or stopper from
2. to free from any stoppage or obstruction; open
3. to draw out the stops on (an organ)