How to uninstall my own wpf application

This is the way I would suggest you to go for achieving what you are up to! Note: The way I explain is what you can do in normal visual studio installer project. For install shield, the steps may look different but it follows same strategy.

1. File System on Target machine -> add a Special Folder, select System Folder
2. Into this system folder Add a file. Browse for msiexec.exe from local System32 folder and add it.
3. Override default properties as: Condition = Not Installed, Permanent = True, System = True, Transitive = True Vital = False
4. Create a new shortcut under the Application Folder, Set Target to the System Folder which you created in the step 1. and point it’s at the msiexec.exe.
5. Rename the shortcut to ‘Uninstall Your Application’.
6. Set the Arguments property to /x [ProductCode] (there is a space in between x and [)
7. Build the project

After you are done with these steps, you would have created your own uninstaller for your application. Now, when you install you application for first time, it will automatically paste the uninstaller exe in the install folder. Next time when you install, the installer should find and execute this uninstaller before installing newer version. For this, you can create a vb script batch file to invoke and execute your uninstaller exe.

Dim WSHShell
Dim oFSO
Dim EXEPath

Set WSHShell = CreateObject("WScript.Shell")
Set oFSO = CreateObject("Scripting.FileSystemObject")

If Not WSHShell Is Nothing Then
    EXEPath = "C:\Program Files (x86)\Your Application Location\Uninstall Your Application.exe"

    If oFSO.FileExists(EXEPath) Then
        WSHShell.Run(EXEPath)
    End If
End If

Store this script as uninstaller.vbs in you application and attach this file in your Application Folder. Now, in your customer actions for install, you need to execute this script before you perform installation.

I hope this helps!

If you just want to install a setup that you built and installed, and it's (for example) a Visual Studio setup project that generated an MSI file then you just need to know the ProductCode of your setup.

Then (in C#) you'd P/Invoke to MsiConfigureProduct and pass in the ProductCode, INSTALLLEVEL_DEFAULT, INSTALLSTATE_ABSENT).

Otherwise can use the command msiexec /x {productcode} with whatever other command line options you choose.

The problem will be that you are trying to uninstall a product from which a program is still running, therefore there's a kind of deadlock.

If you were using WiX there's this:

http://wixtoolset.org/documentation/manual/v3/howtos/files_and_registry/create_uninstall_shortcut.html