Thank you for reaching out to the community for assistance with cancelling your Synapse dedicated pool reservation.
To cancel your reservation, you can follow the steps outlined in the Azure documentation here.
Regarding your billing concerns, cancelling your reservation will stop the billing for the reserved capacity. However, if you have already paid for the entire 3-year reservation, you may be subject to a cancellation fee. You can find more information about the cancellation fees here.
Hope this helps. Do let us know if you any further queries.
If this answers your query, do click Accept Answer
and Yes
for was this answer helpful. And, if you have any further query do let us know.