Didn't `lazbuild --help` tell you something?
forgive me. I saw the "--build-mode" option, but every time after I used it, I saw the binary was generated inside the "debug" folder. So, I thought it wasn't the right option. I just realized that in both of my Debug/Release profiles, the output folders were specified as "debug". So, that flag indeed worked. I verified the generated binary in the release mode, the "Heaptrc" output was indeed removed, as desired.
sorry for overlooking this. case closed.