Today I had to remove some software from a Windows system where there was "unremovable" software.
The traditional way is to go into your configuration screen and then choose the "Program and Features". The list that is shown to you is actually read from the registry. Sometimes there is software in this list that does not give you the option Uninstall.
To deal with such software you got to go in the registry yourself and check for a couple of registry keys.
The starting path is
The UninstallString is a string that will give you a command that when run from the command line will remove the product from Windows. It is a command that uses Windows Installer. A nice source of information about this part of the registry is https://msdn.microsoft.com/en-us/library/aa372105%28VS.85%29.aspx
To hide the uninstall button in "Program and Features" for applications you'll need to find the NoRemove key. If the key is set to (hexadecimal) 1, you will not see the button If the value is set to (hexadecimal) 0, the Uninstall button will be visible.
After a couple of hours removing unwanted software the system was ready to be (ab)used by yours truly.