Hallo Mathew
That’s not possible. Once you purchased a ticket with your official swisspass account, the Tickets and other details to this trip will be registered in your personal swisspass account data.
If you don’t want your trips to be recorded like that, my advice to you is to purchase your tickets as a guest. So, you’ll receive your tickets directly on your E-Mail but they won’t be registered anywhere else in our sbb plattforms.
Wish you a good day. EllenvS.