Can't delete app which is no longer existed on my mountain lion

Question

I kept got notificaiton for update of an app called chopper 2 even though I never bought it. And the even weirder thing is that the account that apple says I bought this app with is not mine. The tragic thing now is that because it was not bought by my account, I don't have the password to update it or delete it.
This app might be from the vendor who sold me this mac book air. They loaded my MBA with tons of software which I cleaned it up by reinstalling the whole os.
How could a ghostly behaved app haunt me after the whole system reinstallation?
Please help me.

Answer 1

You installed a hacked application, originally from the Mac App Store. It contains the receipt for a different application, downloaded from another account. You need to identify and remove the hacked application.
Triple-click anywhere in the line below to select it:
mdfind kMDItemAppStoreHasReceipt=1 | open -f -a TextEdit
Copy the selected text to the Clipboard (command-C).
Launch the Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window (command-V).
A TextEdit window will open with the list of all App Store products you've installed. Compare that list with the list of your purchases from the App Store. To see the complete list, you may need to unhide hidden purchases. If you, or another user of the computer, have download applications from the App Store using other Apple ID accounts, sign in under each of those ID's and check the purchases.
If any of the items in the TextEdit window were not downloaded under an Apple ID known to you, they should be deleted.