Boot Camp Error Code 0xc0000225
Recently I tried uninstalling Windows on my iMac. When I did this using Boot Camp it crashed. At first it appeared as if it was gone, but when turning on my iMac and holding down option I still see "Boot Camp". When I try to boot into it I get error code 0xc0000225. I've already read this article: If you see error codes 0xc000000f or 0xc0000225 when installing Windows 10 - Apple Support (I know it's for installation, but in the first steps it's to remove it before attempting to install it again). This article was no help because in Disk Utility I only see one partition, the one I use for macOS. How exactly do I remove Windows altogether? Also, something of note, ever since this happened my system performance has been terrible.
iMac 21.5", macOS 10.15