Hi @Cátia Sul ,
Welcome to our forum!
Looks like your issue is related to Microsoft Booking, please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. Based on my research, i found that we can refer to the below article to delete a booking calendar in Bookings: Delete a booking calendar in Bookings.
If it doesn't help, in order to better solve your problem, it's suggested that you could post your case in dedicated forum for Microsoft Booking for more professional advice.
Thanks for your understanding and hope your issue would be resolved soon.
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