This command is used to remove a sprite from a moan channel, previously added with Add Sprite To Channel.
If channelId is not specified, the sprite is removed from all the moan channels it is on.
When a sprite killed, it is automatically removed from all moan channels.
spriteNum is the sprite to remove from the moan channel.See also Remove Viewport From Channel, Add Sprite To Channel and Add Viewport To Channel.
channelId is the optional moan channel to remove the sprite from.