use pacmd to undo these changes to pulseaudio sink settings

Question

Recently I discovered this question and answer on askubuntu.com which, while useful, also rendered my sound system unusable for practical purposes.

The commands

pactl load-module module-null-sink sink_name=nullsinkname
pactl move-sink-input nullsinkname steam

My null sinks are still mapped to various applications, even after halt.

I suspect it may be due to the default behavior of the module itself (Load Once: no). I don't know how to turn this off or to restore my system to its original state.

>>> describe-module module-null-sink
Name: module-null-sink
Version: 2.0
Description: Clocked NULL sink
Author: Lennart Poettering
Usage: sink_name=<name of sink> sink_properties=<properties for the sink> format=<sample format> rate=<sample rate> channels=<number of channels> channel_map=<channel map>
Load Once: no

Here's an example of mplayer not working:

>>> list-sink-inputs
1 sink input(s) available.
    index: 63
        driver: <protocol-native.c>
        flags: 
        state: RUNNING
        sink: 6 <rooki>
        volume: 0:  84%
                0: -4.54 dB
                balance 0.00
        muted: no
        current latency: 182.62 ms
        requested latency: 210.00 ms
        sample spec: float32le 1ch 16000Hz
        channel map: mono
                     Mono
        resample method: speex-float-3
        module: 7
        client: 176 <MPlayer>
        properties:
                media.name = "audio stream"
                application.name = "MPlayer"
                native-protocol.peer = "UNIX socket client"
                native-protocol.version = "26"
                application.process.id = "14224"
                application.process.user = "alec"
                application.process.host = "ROOROO"
                application.process.binary = "mplayer"
                application.language = "C"
                window.x11.display = ":0"
                application.process.machine_id = "eec7c6ae60f90bb3921ad16d0000302d"
                application.process.session_id = "eec7c6ae60f90bb3921ad16d0000302d-1345384044.64188-1149507345"
                module-stream-restore.id = "sink-input-by-application-name:MPlayer"

It's been mapped to sink 6, which I called "rooki". I don't know what the original sink was called, or how to undo the mapping.