If you’d like to rename one of your message templates in your account you can! To rename a message template, do the following:
Go to Settings > Reminders.
Select the template you want to edit from the dropdown menu in the Message Templates section.
In the text box that appears with the current message template title, edit and type in the new title of the message template that you would prefer.
Click the Save button next to the message template name to keep the changes.
Once the steps above are completed, you will be able to find the new Message Template title/name in the Messages drop-down menu on your appointment creation form and in the Instant-book Appointment Messages dropdown menu for your Booking settings.
Here's a screencast showing you the above steps: