Since you installed the program in the sandbox. No permentant changes were made to to your computer's sensitive areas (registry, drivers, etc...) and the program does not have access to your system or personal files.
If you empty the sandbox (don't delete it), the program should just disappear, leaving behind no trace it was ever there. Think how handy that will be when you get hit with a fake av, or other driveby nasty. Pretty slick huh.