Well, assuming you can target it with jQuery it should be just as simple as calling remove()
on the element:
$('link[rel=stylesheet]').remove();
That will remove all external stylesheets on the page. If you know part of the url then you can remove just the one you're looking for:
$('link[rel=stylesheet][href~="foo.com"]').remove();
And in Javascript
this is an example of remove all with query selector and foreach array
Array.prototype.forEach.call(document.querySelectorAll('link[rel=stylesheet]'), function(element){
try{
element.parentNode.removeChild(element);
}catch(err){}
});
//or this is similar
var elements = document.querySelectorAll('link[rel=stylesheet]');
for(var i=0;i<elements.length;i++){
elements[i].parentNode.removeChild(elements[i]);
}