Unable to uninstall idm

I installed idm and after some days idm asked for registration, then i tried some crack app it registered idm with fake registeries after that everytime whenever i tried to open idm an error message is displayed as "idm is registered with fake register keys please register now".
So, i decided to uninstall it from my pc, i uninstalled from control panel it disappeared from installed apps. But, remains in system tray and in installed folder. If i opened it, it succesfully opens and says same message as above. so, manually removed all files from installed folder but except two pdf files all are removed. If i tried to remove those two pdf files a error message appears as " unable to delete as these are open in windows explorer" i tried to reinstall but same happens as described above. plz help anyone