Using the applications's built-in uninstaller
Some Mac applications come with their own uninstaller programs. If your mac application does come with its own uninstaller, then that's the best way to uninstall your app .
Trashing the .app bundle using Finder
An app can be uninstalled by going to the /Applications folder using Finder and then, simply moving a .app bundle (or an application folder) into the trash like this:
Uninstalling from the Launchpad
Or you can do it from the OS X Lion (10..7) Launchpad.
In the launchpad (or in a launchpad app drawer), long-click an application icon until the app icons start to wiggle. If the app is removable from the Launchpad, then tiny 'X' should appear on the top left corner of the removable apps. Click on the 'X' to uninstall the app from the Mac - just like the way iOS does it.
Removing app-specific preferences files
However, uninstall will remove the app from the Mac, but can still leave behind the app specific preferences which can take up a lot of space depending on the type of app. This is done to save you from re-configuring all the app preferences again in case you decide to reinstall the application into the system at a later date. You would need to locate these preference files in the Finder if you want to delete the files. They are usually found at the following locations in the user's home library folders:
- ~/Library/Application Support/(App_Name)
You can searching for and delete the app bundles and app preference files manually. That gives you an engineer's control on this task. NOTE: THIS IS FOR ADVANCED USERS ONLY
extracted from: http://guides.macrumors.com/Uninstalling_Applications_in_Mac_OS_X
- Launch Finder and search for the app name (hopefully unique, such as Skype)
- You can narrow the search to specific folders or search your whole Mac
- Searching for "File Name" rather than "Contents" usually provides better results.
- Click the + button below the search term to add criteria
- Click the search criteria drop-down and select "Other...", then "System files"
- Click the "don't include" and change to "include"
- Sort by name, kind, date, etc. to identify components of the app, such as folders, .plist files, cache files. etc.
- Delete all files and folders related to the app.
- Do NOT empty your Trash until you've determined that everything is working OK, in case you need to restore something you deleted by accident.
- A reboot might be necessary to completely remove some apps.
Mac App Uninstaller tools
There are some free app uninstaller tools that come with a graphical user interface.
But they don't always do the best job in terms of locating and remove the app-specific preferences files.
[edit: the AppTrap web site says "With AppTrap, when you move an application to the trash, you're automatically asked if you want to move the associated preference files as well. "... well AppCleaner has that feature in itself as well, and they call it SmartDelete]