Customizable Mall Apps
You’ve downloaded an iPhone, iPod Touch or iPad App from the App Store, and have now discovered you don’t really want or need that App. This tutorial will show you how to delete it from your iPhone, iPod Touch and/or iPad.
On your Home screen, locate the App you want to delete. For this example, I’ll use WeatherBug.

Tap and hold down the icon of the App you want to uninstall. After a few seconds your screen will start to “wiggle” and an X will appear next to each of the Apps you’ve installed via the App Store.
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Note: if the X doesn’t appear at all, skip down to step #7 below.
Tap the X next to the icon of the App you want to remove. When prompted, select Delete.
image: http://www.simplehelp.net/images/delapps/img03a.png

And now it’s gone.
image: http://www.simplehelp.net/images/delapps/img04a.png

If the application is listed in your iTunes Applications as well, you’ll want to remove it from there – or else it will re-install the next time you sync. Alternately you can keep the app in your iTunes Applications, and set iTunes not to sync all applications, just the ones you want to keep. See the Applications tab of your device the next time it’s connected in iTunes for syncing options.
You cannot delete certain apps – typically the ones that come pre-loaded on your iPhone, iPod Touch or iPad – such as Stocks, Weather, Safari etc. You can use this tutorial to “move” them to another screen (perhaps the ‘last’ one) so that you don’t have to see them and/or make room for the Apps you use more frequently.
If you don’t see an X mark at all, on any of your Apps – you’ll need to enable an existing Restriction before you can uninstall Apps. Start out by tapping the Settings button from your Home screen.
image: http://www.simplehelp.net/images/iphone_ipad_settings_button.png

Scroll down to the General tab and select it.
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Now scroll to Restrictions and select that.
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When prompted, enter your 4 digit PIN code. If you don’t know your 4 digit PIN code – start guessing. Ask a family member who may have set it up for you. If you can’t determine the 4 digit PIN code, you will not be able to make any changes.
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Scroll down to the Allow: section of the Disable Restrictions screen. Look for the entry titled Deleting Apps. Slide the button next to it from OFF to ON.
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Double-check to make sure the Deleting Apps entry is set to ON.
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Now jump back to step #2 and you should have no problem uninstalling Apps from your iPhone, iPod Touch or iPad.
image: http://www.simplehelp.net/images/delapps/img12a.png

Note: if you’d like to disable the ability for Apps to be installed at all on an iPhone, see this tutorial on how to stop Apps from being installed on an iPhone, iPad or iPod Touch. This can be particularly useful for parents who want to be able to control which Apps are installed on their childs iDevice.
Read more at http://www.simplehelp.net/2008/07/12/how-to-delete-apps-from-your-ipod-touch-or-iphone/#3sQ2ZKWKP4tSUlxl.99