Question: how to unregister ocx file?
Answer: Select Start > Run (or in Windows 8, 7 or Vista press the Windows logo key + R key )
Type Regsvr32 /u {Filename.ocx} [There is one space both before and after /u. Do not type the {} braces. ... 
Click the OK button. ... 
Then re-register the file by running Regsvr32 {Filename.ocx or .dll} (as described above.