something like this:
var
i, len,
target_class = 'class_name',
$iframes = $( 'iframe', top.document ); // <-- add top.document
for ( i = 0, len = $iframes.length; i < len; ++i ) {
$iframes.eq( i ).contents().find( '.'+ target_class ).remove();
}
$( '.'+ target_class, top.document ).remove(); // <-- add top.document
or with vanilla js:
var
i, len,
target_class = 'class_name',
iframes = top.document.getElementsByTagName( 'iframe' ), // <-- add top.document
removeByClass = function ( doc, class_name ) {
var i, len, el,
toRemoves = doc.getElementsByClassName( class_name );
for ( i = 0, len = toRemoves.length; i < len; ++i ) {
el = toRemoves[ i ];
if ( el.parentNode ) {
el.parentNode.removeChild( el );
}
}
};
for ( i = 0, len = iframes.length; i < len; ++i ) {
removeByClass( iframes[ i ].contentDocument, target_class );
}
removeByClass( top.document, target_class ); // <-- add top.document
EDIT
Added the possibility to call from inside the iframes, but they MUST be from the same domain!!