The players list should be customizable

The player list will in future be determined by the gsettings entry for indicator sound (from release 0.5.4 targeted 23/12/2010). More information can be found on the spec about this.

https://wiki.ubuntu.com/SoundMenu#Registration%20process

This will allow users to add or subtract individual players from the menu at any given time from the preferences of the individual players.

This should be fixed as of today's release. It up to the clients to their side of the work to write the Gsettings entry.

status: Fix Released → Fix Committed

But how can I remove links to other player?

Each player should follow the spec on the wiki (wiki.ubuntu.com/SoundMenu) which outlines the preferred UI to enable players to be added or removed from the menu. As it stands currently this is simply achieved by adding or removing the desktop file name of the application (minus the .desktop extension) to or from the blacklist-media-players gsettings entry for com.canonical.indicators.sound.
Hopefully for alpha2 I will make this even easier whereby it will be just a simple dbus method call.
If you want to remove other players for an interim solution (until players have their UI in order) you can use gsettings command line tool to manually add the name of the player(s) that you would not like to see in the menu.
The name being the name of the players desktop file minus the .desktop extension.

An example would be

gsettings set com.canonical.indicators.sound blacklisted-media-players "['$PLAYERS-DESKTOP-FILE-NAME']"

gsettings set com.canonical.indicators.sound blacklisted-media-players "['rhythmbox']"

GLib-GIO-ERROR **: Settings schema 'com.canonical.indicators.sound' is not installed

aborting...

Sorry, I was using 0.5.0.1-0ubuntu2 version.

Okay to be ultimately complete this, I have provided a dbus method to simply add or remove a player from the menu, Obviously it uses gsettings in the background but for those of you who can't touch gsettings please use this instead.