option prefix always has underscore, so include it just to be safe

Author: dannyvankooten

uninstall.php

@@ -8,7 +8,7 @@
 global $wpdb;
 
 // Delete all MC4WP related options and transients
-$wpdb->query("DELETE FROM {$wpdb->options} WHERE option_name = 'mc4wp' OR option_name LIKE 'mc4wp%' OR option_name LIKE '_transient_mc4wp_%' OR option_name LIKE '_transient_timeout_mc4wp_%';");
+$wpdb->query("DELETE FROM {$wpdb->options} WHERE option_name = 'mc4wp' OR option_name LIKE 'mc4wp_%' OR option_name LIKE '_transient_mc4wp_%' OR option_name LIKE '_transient_timeout_mc4wp_%';");
 
 // Delete all MC4WP forms + settings
 $wpdb->query("DELETE p, pm FROM {$wpdb->posts} p LEFT JOIN {$wpdb->postmeta} pm ON pm.post_id = p.ID WHERE p.post_type = 'mc4wp-form';");