You can make a cancellation request from the "Bookings" section of your Click&Boat account. Click on "Access" then click on "Cancel booking".
If you subscribed to Assur Travel insurance at the time of booking, you will find your contract under "Bookings" > "Access" > "Assur Travel Contract"
You can send your request to Assur Travel regarding the cancellation of your booking by calling this number +33 (0) 32 03 07 41 2 or via the following email address: contact.gestion@assur-travel.com