Fortunately ‘buddypress-member-types-pro’ plugin does not show it’s ‘Select member type’ drop-down list in case member types list is empty. So we can use this to hide it:

add_filter( 'bp_get_member_types', 'remove_bpmtp_select_member_type', 100 );

function remove_bpmtp_select_member_type( $types ) {
    $user = wp_get_current_user();
    if ( is_array($user->roles ) && in_array('users_administrator', $user->roles ) ) {
        $types = array();
    return $types;

Just replace ‘users_administrator’ at the code above with your own role ID and place this code to your active theme functions.php file or set it as a Must Use plugin.