how to rename a plugin [shortcode] in all posts?

hi, i need to rename a gallery [shortcode] in all posts (300), because i want to change the plugin so the shortcode is with different name.

I know only how to remove a [shortcode] from all posts with the following:

add_shortcode(‘shorcodename’, ‘my_remove_shortcode’);
add_shortcode(‘the-shortcode-to-remove-here’, ‘my_remove_shortcode’);
function my_remove_shortcode(){
return ”;
}

but i want to rename it, how?

thanks