Quote from: Maddd Cuan on Today at 12:45:05 PM

So the question is : can we canceling the trasactions through decrease of fee(before get the blocks)? like do RBF with lowest sat/bytes ?

What you are actually doing when increasing the fee is to create a second transaction spending the same funds as the first one which has the replacable flag set.
By using a higher fee, miner will prioritize the second (replacing) transaction.

If you would choose a smaller fee, there is no incentive for the miner to include your second transaction instead of the first one.

Once a (valid) transaction is broadcasted, it can be confirmed. You can't really stop it. You can only try to stop it by giving a miner the incentive to not include it (e.g. by creating a RBF transaction to yourself with a higher fee).

So the answer is: No, that's not possible.