Security Update for SQL Server 2012 Service Pack 2 (KB3045321) update problem - error code 858C001E, and error code 1642

I have an "important update" to install that won't install. It is Security Update for SQL Server 2012 Service Pack 2 (KB3045321). It fails with error code 858C001E. I can't find any help on that error.
According to the event viewer there were three errors from MsiInstaller:
Product: SQL Server 2012 Database Engine Services - Update '{2FCB8511-8FA3-4CFD-B6AD-7B48F91A418E}' could not be installed. Error code 1642. Additional information is available in the log file C:\Windows\TEMP\MSI8bc0f.LOG.
Product: SQL Server 2012 Full text search - Update '{231E355A-23FF-4D51-984B-26623B3B26CC}' could not be installed. Error code 1642. Additional information is available in the log file C:\Windows\TEMP\MSI8bc10.LOG.
Product: SQL Server 2012 Reporting Services - Update '{7E4F64D0-D295-4410-BD36-E8B49D06A50E}' could not be installed. Error code 1642. Additional information is available in the log file C:\Windows\TEMP\MSI8bc11.LOG.
I think error code 1642 means it could not find the product to update. I don't use SQL Server. I installed it a while back to experiment only, so I uninstalled it today, but Windows Update seems to still think I need the update and, of course, it still fails.
Any suggestions?
Rob