I can't say whether this is a rogue programme or legitimate. There is a rogue called reg clean but whether it's the same one I don't know.
Did you get it from here?
If so these are their removal instructions:
1. Click Start button on your taskbar and select Control Panel.
2. Double-click the Add/Remove Programs icon. (On Windows 7 and Vista, double-click the Programs and Features icon.)
3. In the new window that opens, select the name of the program you wish to uninstall.
4. Now, click the Remove option. (On Windows 7 and Vista, click the Uninstall option.)
They say this will remove the program from your system.
If not I suggest a visit to our Hijackthis forum.
I note there is no pre-purchase opportunity to try this programme.