In this example, all emails whose sender is a@bc.com are deleted from the queue.

postqueue -j | jq -r ‘select(.sender == “a@bc.com”) | .queue_id’ | xargs -I {} postsuper -d {}

jq must be installed ( apt install jq )

for other filtering criteria

postqueue -j | jq

You can type and see the fields in the json output.