How to allow users to give weak password on “My Account” page?

Hello,

Thank you for the question.

Here is a useful tutorial that should help you disable password strength meter https://nicola.blog/2016/01/27/remove-the-password-strength-meter-on-the-checkout-page/

According to this article all you need to do is to insert this code snippet to the functions.php file in your child theme

function wc_ninja_remove_password_strength() {
	if ( wp_script_is( 'wc-password-strength-meter', 'enqueued' ) ) {
		wp_dequeue_script( 'wc-password-strength-meter' );
	}
}
add_action( 'wp_print_scripts', 'wc_ninja_remove_password_strength', 100 );

Regards