Prevent users from cancelling their membership or checking out for a new one.

redirect_from_checkout_and_cancel.php

<?php

// Copy from below here...

/**
 * Prevent users from cancelling their membership or checking out for a new one.
 */
function my_pmpro_redirect_from_checkout_and_cancel() {
	global $pmpro_pages;

	$user_level = pmpro_getMembershipLevelForUser();
	if ( empty( $user_level ) || ! function_exists( 'pmprosm_isSponsoredLevel' ) ) {
		return;
	}

	if ( ( ! empty($pmpro_pages['cancel']) && is_page($pmpro_pages['cancel'] ) ) ||
		( ! empty($pmpro_pages['levels']) && is_page($pmpro_pages['levels'] ) ) ||
		( ! empty($pmpro_pages['checkout']) && is_page($pmpro_pages['checkout'] ) ) ) {
		if ( ! empty( $pmpro_pages['account'] ) ) {
			wp_redirect(pmpro_url('account'));
			exit;
		} else {
			wp_redirect( home_url() );
		}
	}
}
add_action('template_redirect', 'my_pmpro_redirect_from_checkout_and_cancel', 5);

/**
 * Hide action links on profile page.
 */
function my_pmpro_hide_action_links() {
	global $pmpro_pages;

	$user_level = pmpro_getMembershipLevelForUser();
	if ( empty( $user_level ) ) {
		return;
	}

	if ( is_page( $pmpro_pages['account'] ) ) {
	?>
		<style>
			.pmpro_actionlinks { display:none; }
		</style>
	<?php
	}
}
add_action( 'wp_footer', 'my_pmpro_hide_action_links' );