You can choose to enable the shell integration for the installation of SmartSVN , when using the MSI installersinstaller bundle. It's also recommended to have SmartSVN automatically be started with the system startup, so the shell integration is available immediately. The installers installer offer a corresponding option which will add SmartSVN to the Autostart section, starting SmartSVN in server mode.
Windows supports only a quiet small number of overlay icons. On Windows 10, for example, by default too much overlay handlers are already installed and hence you will see a confirmation dialog that will ask whether to put the SmartSVN overlay icons before the other overlay icons. If you choose not to do that, some overlay icons, e.g. for conflicted files, will not be shown.
The shell integration will be uninstalled together with SmartSVN. You can also uninstall the shell integration independently from the Control Panel, Software, using Repair there.