How to remove all event handlers for child elements of a parent element using JQuery

You can use unbind() if you used bind() to attach the events.

  $('#foo').children().unbind();
  $('#foo').children('.class').unbind(); //You can give selector for limiting clildren

or

Use off() if you used on() to bind events.

 $('#foo').children().off();
 $('#foo').children('class').off();   //You can give selector for limiting clildren

For removing the event from all descendants instead of direct children you can use Descendant Selector (“ancestor descendant”) .

$('#foo *').off(); 

Yeap - use off() with no params - that will unbind all events bound.

$('#parent *').off();

If you meant literally children, i.e. not children OR descendants, use #parent > * instead.

I also wondered if I needed to manually unbind every children of the removed element.

From jquery documentation you shouldn't:

jquery docs for remove

If we had any number of nested elements inside , they would be removed, too. Other jQuery constructs such as data or event handlers are erased as well.

Since I was curious if this was true I checked the source code:

function remove( elem, selector, keepData ) {
    var node,
        nodes = selector ? jQuery.filter( selector, elem ) : elem,
        i = 0;

    for ( ; ( node = nodes[ i ] ) != null; i++ ) {
        if ( !keepData && node.nodeType === 1 ) {
            jQuery.cleanData( getAll( node ) );
        }

        if ( node.parentNode ) {
            if ( keepData && jQuery.contains( node.ownerDocument, node ) ) {
                setGlobalEval( getAll( node, "script" ) );
            }
            node.parentNode.removeChild( node );
        }
    }

    return elem;
}

as you can see:

jQuery.cleanData( getAll( node ) );

is cleaning all the events of all the childrens of the removed element.

So in the end: if you use $(element).remove() or .empty(), you are already memory leak safe!