Restarting the computer should reset the fans to the computers control. I would also recommend making sure its not in the startup applications so it doesn't turn on when you login, and possibly take control of your fans again.
If that doesn't work try doing a SMC reset, this will almost surely reset the fans to system control. Again with this one, I would recommend you make sure it isn't in your startup applications.
How to reset the SMC
Remove Start Up Application
If you still want to use software to control the fan I would recommend using this software. I personally use it to monitor my computers temperature and to control the fans.