Just noticed this now - hence the late comment.
Routerstats is a standalone program, which means that it doesnt impact on any of the system files (as HP already said).
Standalone programs can be run from anywhere - for example from a usb stick. Because they dont use any changes to the system, nor leave parts of the program scattered all over the place, when you delete the exe file thats the program gone.
Other programs (say AV) will make changes to system files and leave parts of the program on various parts of the drive... therefore they need an uninstall process to keep track of what its put where. If you just delete the .exe without doing a proper install then parts of the program will always remain on your drive and in the registry. These types of program are the ones that you will find in CP.