TestComplete samples (both built-in and additional) are located in the <Users>\Public\Public Documents\TestComplete 15 Samples folder.
Some file managers display the Public Documents folder as Documents.
Desktop samples demonstrate the main approaches to testing desktop applications.
These samples are part of the additional sample package. To use them, download this package from https://support.smartbear.com/testcomplete/downloads/samples/ and install it.
After the installation is over, you can find the samples in the <TestComplete 15 Samples>\Desktop folder.