I don't seem to have this cab file anywhere in my Windows folder or my C: drive. The Windows Update Catalogue only has the MSU file to download.
I was rereading the uninstall notes and it now seems to say you can only remove the LCU and not the SSU, which is what I thought I read originally:
If you want to remove the LCU
To remove the LCU after installing the combined SSU and LCU package, use the DISM/Remove-Package command line option with the LCU package name as the argument. You can find the package name by using this command: DISM /online /get-packages.
Running Windows Update Standalone Installer (wusa.exe) with the /uninstallswitch on the combined package will not work because the combined package contains the SSU. You cannot remove the SSU from the system after installation.