hide the elementor templates menu

You’ll need a 3rd-party plugin to do this. There are several, I believe. Adminize and Admin Menu Editor are two I can think of, but I know Adminize at least has to do some sort of workaround for Elementor, so dig into their support forum to find the answer to that. Alternatively, you can add your own function by following a guide such as https://isabelcastillo.com/remove-menu-items-wordpress-dashboard