unset($doc->_scripts[JUri::base(true)'/path/to/file.js'])
is mostly how to do it, some scripts might add the full url and some might not.
So here is a better way to go about it if you want everything removed.
$doc->_scripts = array();
//if you need to re include libraries
JHtml::_('jquery.framework');
JHtml::_('behavior.framework');
//if the array trick does not work you could do
for($i=0;$i<count($doc->_scripts);$i++){
//in here you could stop it from removing specific files by looking for specific file names
$get_file = explode('/',$doc->_scripts[$i]);
$get_file = end($get_file);
//many more ways to do this, chains of if statements can get messy
switch($get_file){
case 'jquery.js':
case 'boostrap.js';
break;
default:
unset($doc->_scripts[$i]);
break;
}
}