First of all thank you very much for using the WP Travel plugin.
Now coming back to your query, if you would like to only display “Booking Only” option then disabling all the payment gateway from the Trips > Settings will only allow you to display the booking form escaping all the cart and checkout and process.
Additionally, if you would like to display only “Booking with Payment” option in final checkout page then you have to add below given code in your child theme functions.php file.
Please refer to below-given link to know how to create the child theme.
Thank you, I modified the booking with payment code to “Booking Only” and it works.
I need this instead of disabling “payment method” as otherwise you do not serve calendar on the booking cart to customers to choose from different fixed multiple dates.