@mcrudd It sounds like you have Origin set to start with Windows, which may itself be the issue. Please change that setting: in Origin, hover over your username, select Application Settings, and under Application (the first header) scroll down to Startup options and turn off the setting to automatically start Origin.
If that doesn't help, clear Origin's cache and then uninstall it "the hard way."
https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/
https://help.ea.com/en-us/help/origin/origin/manually-uninstalling-origin/
A restart usually fixes the problem of a file being in use, although it wouldn't if Origin were still starting with Windows. In that case, go through the Task Manager looking for the Origin Client Service and Origin Web Helper Service (both background tasks), and end both. They'll have the orange Origin logo and therefore be easy to spot.
When reinstalling Origin, use the full installer, and run it as an admin: right-click on the download and select "Run as administrator." This is a direct download link:
http://download.dm.origin.com/origin/live/OriginSetup.exe