drupal programmatically disable or remove node create node link(s)

In the context of organic groups, I am writing a module which will stop users who are not members of a group from adding group posts into that group.

My module currently sets the permissions necessary and detects whether a user has the permission.

So when a user(s) are looking at a group page, I want to disable/remove the standard link to create group posts.

Try this method.

function mymodule_menu_alter(&$items) {
    global $user;
    // Perform code for finding out users permissions.
    // lets suppose we set true or false to $restricted after all
    if ($restricted && isset($items['node/add/yourtype'])) {
        $items['node/add/yourtype']['access arguments'] = FALSE;
        // or unset($items['node/add/yourtype']) to remove item for user
    }
}