If you want to discard your Terminal state, you have to quit with holding the Alt key. The menu will change from "Quit Terminal" to "Quit and close all windows.

If you want to discard your Terminal state, you have to quit with holding the Alt key. The menu will change from "Quit Terminal" to "Quit and close all windows".

You can also make it effective with the "normal" quit Cmd + Q, this way:

1. Open your terminal
2. Delete the content of the saved state folder: rm -rf ~/Library/Saved\ Application\ State/com.apple.Terminal.savedState/*
3. Lock the folder: chflags uchg ~/Library/Saved\ Application\ State/com.apple.Terminal.savedState/
4. Now, every time you quit your terminal, it won't be saved