How to select ALL children (in any level) from a parent in jQuery?

Use jQuery.find() to find children more than one level deep.

The .find() and .children() methods are similar, except that the
latter only travels a single level down the DOM tree.

$('#google_translate_element').find('*').unbind('click');

You need the '*' in find():

Unlike in the rest of the tree traversal methods, the selector
expression is required in a call to .find(). If we need to retrieve
all of the descendant elements, we can pass in the universal selector
‘*’ to accomplish this.