Open a DOS box and do format c:
Obviously that's sarcasm but seriously, the Windows registry is hopeless for keeping tidy. There are probably freeware programs (or paid ones) that clean the registry of crud; hopefully they don't break things.
This is why back in the old days of Windows 95 and Windows NT that I would wipe the disk and reinstall Windows once a year. These days I just don't look and ignore it. As long as those registry entries aren't causing any problems you should learn to ignore them.