Hi there! I hope you are well. My name is, Zadee. I'm an Independent Advisor and a Microsoft user like you. Sorry to hear about your experience. I'll try my best to help you today.
To me, your time is more important than even trying to troubleshoot this possible bug. First, I'd like to let you know that this is not a resolution that I am offering but info, and that I am experiencing this exact same issue and many others where the 2nd keyboard layout does not exist in the keyboard setting for you to delete, but still, the 2nd layout would show up in the system tray. I have tried the registry method as well by removing a key but the key just keeps on coming back after reboot. This is the thread where we have tried to figure it out.
https://answers.microsoft.com/en-us/windows/for...
You can certainly try to delete the key of the keyboard layout you want to remove, in the registry, but I think it's just going to return after a reboot. But maybe it's going to be different for you.
Otherwise, please send feedback to MS through the Feedback Hub (Windows + F). Thank you.