On iOS, if you want to remove all settings and documents for an application during development and start from a clean install, you just need to delete it. However, on the Mac, removing the application bundle does not clear all preferences for that application.
How can you test an application from a clean start on the Mac?
Try deleting any related folders or files in ~/Library/Preferences/ and ~/Library/Application Support/.
Just delete any files that the app has stored in the ~/library/applicationsupport folder, and trash the ~/library/preferences/com.yourappid.plist file.
On Lion the ~/library folder is hidden, so get to it by using the finder's go > go to folder menu.
You could also try changing the bundle ID so the next time you build it will think it's a different app.
