"Run it up flagpole" is an idiom that means to test or trial something. The antonyms for this phrase could include words like reject, ignore, overlook, or discard. Reject means to refuse to accept or consider something, while ignore means to pay no attention to something. Overlook means to fail to notice something, while discard means to get rid of something as no longer useful or desirable. Therefore, if you are not interested in testing or trying something, you can choose to reject, ignore, overlook, or discard it altogether, instead of running it up the flagpole to see how it flies.