If you select an overdue Notezilla sticky note from the notes list and tap on top right options button, you will see the " Dismiss" option. You can use this to dismiss a reminder.
Note: If it is a repeated reminder, then the reminder will be rescheduled to the next reminder date.
To completely remove the Notezilla sticky note reminder, go to reminder options and choose the "Remove" button.
Refer to the pictures below on your I-Phone :