From time to time, I stumble upon applications that are hard to remove. Sometimes their Add/Remove Programs entry disappears for whatever reason or they don’t have a handy Uninstall shortcut available, etc. The problems vary from case to case. That’s why I decided to make a roundup of all the methods that can be used to remove programs and apps, both in Windows 7 and Windows 8.
1. Uninstall Programs from the Control Panel
This is the method known by most people. It works great for all desktop applications but it cannot be used for Windows 8 apps.

Go to "Control Panel -> Programs -> Programs and Features", select the application you want to remove, click or tap Uninstall and follow the wizard.
2. Uninstall Programs Using their Uninstall Shortcuts
Most desktop applications, when installed, create at least an Uninstall shortcut. This is generally found in the application’s folder in the Start Menu (in Windows Vista, Windows 7, etc) or the Start screen (in Windows 8).

Uninstall shortcuts are sometimes also placed on the Desktop. Click on them to launch the uninstall procedure.
3. Uninstall Programs Using their Uninstall.exe
Many programs (especially those which create Uninstall shortcuts) have an executable file named uninstall.exe or something along these lines. This file is always found in the installation folder of that application.

Run it and follow the steps required to uninstall the program.
4. Uninstall Programs Using Their Setup MSI File
Some programs (like the 64-bit version of 7-Zip) do not use a setup.exe file for their installation. Instead their setup file has the extension ".msi". This format is used by the Windows Installer, a special installation format created by Microsoft for its Windows operating systems.

The desktop applications that use an ".msi" installer are very easy to uninstall. You right click on their setup file and click Uninstall.
The removal can be triggered also from the command line. Open the Command Prompt as administrator and type "msiexec /x " followed by the name of the ".msi" file used by the program you want to remove.

You can also add other command line parameters to control the way the uninstall is done. For more information, check this article from Microsoft: Msiexec (command-line options).
5. Uninstall Windows 8 Apps & Desktop Applications from the Start screen
All the methods covered so far apply only to traditional desktop applications. But what about Windows 8 apps? How do you remove those?
Unfortunately there is only one way to do it. Right click or press and hold on their tile, to bring up the contextual menu on the bottom. Then, press Uninstall. The app is then removed in a few seconds without other prompts and confirmations. If an app no longer has a tile on the Start screen, simply search for it, right click or press and hold on the appropriate search result and then press Uninstall.

You can do the same with desktop applications. However, you are taken to the Programs and Features window in Control Panel, from where you can run the uninstall.
6. Use a Specialized Software Uninstaller
There are programs that can be used to cleanup other programs. Some even remove leftovers from the uninstall process, both files and registry entries.
We did quite a bit of research in this area and we have two reviews you should read: Roundup of Software Uninstallers - Reviewing IObit vs Ashampoo vs Revo & Removing Bloat & Crapware with PC Decrapifier or SlimComputer.
If you are looking for a decent tool that can help with removing other programs, these articles will help you find what you are looking for.
Conclusion
I hope that I managed to cover all the ways to remove both desktop applications and Windows 8 apps. If you know other methods, don’t hesitate to share them via the comments form below.