Need to change the text on a button (remove wording)

Hi is there a simple way to change the text on a button? On my Booking page in the Guest details form there is a button on the bottom that reads Book Now $ Pay Deposit

http://www.littleriverbnb.com.au/?page_id=9

I need to change that text to Confirm your booking, can you help me with this?

cheers Kinnear