<?php // remove this line if not needed

add_action( 'init', 'sv_memberships_delete_user_memberships' );

function sv_memberships_delete_user_memberships() {
	global $wpdb;

	if ( $user = get_user_by( 'email', 'EMAIL-ADDRESS' ) ) {

		$wpdb->delete(
      "{$wpdb->prefix}posts",
			array(
				'post_author' => (int) $user->ID,
				'post_type'   => 'wc_user_membership',
				'post_status' => 'wcm-pending',
			),
      array( '%d', '%s', '%s' )
		);
	}
}