Remove 'Renew' link and prevent checkout if user already has membership level

my_pmpro_prevent_renewal.php

<?php

// Copy from below here.

add_action('pmpro_is_level_expiring_soon', '__return_false', 10, 2);

// Prevent registration and display error message when checking out
// for level that the user already has.
function my_pmpro_prevent_renewal( $continue ) {

	global $pmpro_level;

	if ( pmpro_hasMembershipLevel( $pmpro_level->id ) ) {
		$continue = false;
		pmpro_setMessage( 'You already have this level.', 'pmpro_error' );
	}

	return $continue;
}
add_filter( 'pmpro_registration_checks', 'my_pmpro_prevent_renewal' );