Set Up Free Cancellation
Set softCancellations=true
in the URL and then send a transaction to self with the same nonce as the one you want to cancel.
note
This will stop MEV Blocker from broadcasting your previous transaction (it may still get included in rare conditions if it has been broadcasted before). This can be enabled only on /noreverts
or /fullprivacy
endpoints, soft cancellations won't work on /fast
(the default).