How to edit the link within the yellow frame from http://themes.themegoods.com/grandspa/demo/booking/ is http://www.healthlandbodywork.com/booking/
If that is a plugin, maybe you need to search for the file that is setting that url to the button on the code.
If you can’t find it, you might add a new custom button with the link you want to set the new link to.
You can use this link to reach the help desk of Grand Spa theme.
P.S: Don’t forget to check the documentation of the theme. Maybe there is written about this.