I’m a little confused, you’re using approle but don’t want to use your secret id? What’s the purpose of the approle then?
Maybe you mean you don’t want the approle to linger after use? If so you can set the use secret_id_num_uses to 1 … which means the secret id expires after a successful authentication (during the TTL). I have not test this, but my guess is that setting the TTL of a secret-id to 0 would be the same as not setting it and the TTL reverts to the default of cluster max-ttl.