Refund

You have posted this on the partner forum so we cannot help with this.  Contact booking.com help team using Inbox icon on Extranet or give them a call see link for local phone numbers. 

https://partner.booking.com/en-us/help/where-you-can-reach-us

Hi Vignaud 

1. Simply open reservation details.  
2. Message the guest first to say you are cancelling and that they will receive notification that requires then to click accept in order for full refund to be processed by BdC  
3. Wait for guest to do so, then reservation status updates to cancelled

Kind Regards

PS : please take the time to complete your profile and add the property listing link

How & Why Add your Listing to your Partner Community Profile

Contact BdC- Location of Partner Only Phone number and Message methods