NOTE: this post has been superceded. See the definitive guide to turning of Resume for good>>here!<<

This is going to be a major pain for a lot of people, including me!

One of the main reasons I do Cmd-Q (Quit command) is precisely because I want the app to open in a default mode and not to re-open what I was just doing. This is particularly the case if an app goes a bit squiffy or is just not doing what I want it to do.

One way to avoid Resume is to use the option key when you quit. Use the hotkey combination

‘Opt + Cmd + Q‘

or chose Quit from the application menu while holding down the option key. That will both quit the program and discard all current windows. However, if you want to turn off Resume completely, here’s how to do it:

1. Go to the Apple icon in the top left and choose ‘System Preferences’.

2. The first icon at the top is ‘General’. Choose that, then look down the bottom for an option that says ‘Restore windows when quitting and re-opening apps’. You need to UN-check that box to turn of Resume.

However, that’s not the end of Resume, as epbernstein kindly pointed out in the Commments below. Lion will still re-open all your un-quitted apps if you do a restart. In order to avoid this, you need to make sure you un-check the dialogue box in the close-down/restart menu:

By default, this will always be checked, so you’ll have to remember to un-check it every time. Alternatively, you can install and run a script to make this dialog box ineffective (it’ll still show it’s checked, but it won’t work). This is not an ideal solution since it means that if you forget (or someone else using your machine doesn’t know), there’s no indication that the feature is ‘off’. However, if you’re desperate to make sure this feature is off, this looks like the best option so far. 

In case you didn’t see the note at the top of the page:😉
NOTE: this post has been superceded. See the definitive guide to turning of Resume for good>>here!<<