Remove event

For example I have 2 playlists: PL1 and PL2. I load PL1 and set some function (for example fun1()) to onPlaylistItem() event. Then I load PL2 and set another function (for example fun2()) to the same event. But after that both fun1() and fun2() functions are executed, but I need only fun2().
How can I fix that? Is there some function to remove event listeners?