Only let this specific users access the Paid Memberships Pro Reports admin page.

my_pmpro_user_has_cap.php

<?php
function my_pmpro_user_has_cap($allcaps, $caps, $args, $user)
{
	if($user->ID !== 1)
		unset($allcaps['pmpro_reports']);
	
	return $allcaps;
}
add_filter('user_has_cap', 'my_pmpro_user_has_cap', 10, 4);