At this time, you can not remove the canceling option on the booking page and email confirmations.
In this case, you can toggle between send or don't send a confirmation and, I don't think you want that.
Microsoft is currently requesting ideas to improve this app. I encourage you to post your request on the Microsoft Booking Ideas page. with details why you need it and how you plan to use it. This will allow the MS product managers to review your requirement and give the end-users the ability to vote. You also have the ability to vote on other requests.
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