Question

And also, how to remove it then?

Answer 1

// we're in some internal scope here
var x = 10;
var fn = function( e ) {
    wrappedFunction( e, x );
}

//add
o.addEventListener( 'click', fn, false );

// create remover
var remover = function() {
    o.removeEventListener( 'click', fn, false );
}


//save the remover for later or return it - when it's called from whatever scope the event is removed
remover();