Disable password reset option in WordPress. Source: https://wpchannel.com/desactiver-remise-a-zero-mot-passe-wordpress/

disable-password-reset.php

<?php

/*
 * Plugin Name: Password Reset Removed
 * Description: Removes the ability for non-admin users to change/reset their passwords
 * Version: 1.1
 * Author: Derek Herman. Modified by Juliob Potier.
*/

add_filter('show_password_fields', 'baw_prr_i_am_admin');
add_filter('allow_password_reset', 'baw_prr_i_am_admin');
add_filter('gettext', 'baw_prr_remove_me');

function baw_prr_i_am_admin() {
    return is_admin() && current_user_can('administrator');
}

function baw_prr_remove_me($text) {
    return str_replace(array('Lost your password?', 'Lost your password'), '', trim($text, '?'));
}

function baw_prr_no_password_change($dummy1, $dummy2, $user) {
    if (!baw_prr_i_am_admin()) unset($user->user_pass);
}
add_action('user_profile_update_errors', 'baw_prr_no_password_change', 10, 3);