I did some brief (but effective) research, and decided I didn’t want to spend personal time making sure there wasn’t already a topic or solution for this.
Quick summary: you don’t implement an uninstaller for the installer service. Running the TCHC app uninstaller doesn’t remove the associated service, which is basic user-experience territory. The solution I’m seeing commonly, is to manually delete the service. Of course, the service is still running after installation, so one also needs to stop that service first.
There should be a point in the flow of uninstallation that asks the user if they want stop that service and uninstall it. I won’t get into the technicals of this from a software engineering POV or junior security concepts… but leaving a latent service running and installed also raises red flags for security problems and system performance considerations. At an even more basic level, general garbage collection and cleaning up after yourself shows care and expertise to your users.
I don’t assume any nefarious behavior from TCHC, rather those topics I touch on here are objective factoids.