Userscript, so that he would remove the default checkboxes on the site?

Question

JavaScript

There is a site on which checkboxes are set by default on some options, how to write a script that would change the default checkboxes.
I don’t understand scripts from the word at all, but I hope to do it in the image and likeness. So some example is needed.

Answer 1

For example:

var array = document.querySelectorAll('input[type=checkbox]'), i;
for(i = array.length; i--;) {
    if(array[i].checked) array[i].checked = false;
}

Answer 2

If with jQuery, then so

$('input[type=checkbox]:checked').prop( "checked", false );