Xiaomi
Remove a Keyboard Language auf Xiaomi
Every extra language you add to the keyboard stays active until you delete it yourself. MIUI keeps each installed layout in memory, which is why the language switcher gets longer and slower the more languages you tried at some point.
The setting responsible for this lives in Tap on Settings ➔ Tap on Additional settings ➔ Tap on Languages & input ➔ Tap on Manage keyboards. From there, open Tap on Settings ➔ Tap on Languages ➔ Tap on Edit.
Inside the edit view, tap Select a Language/Layout next to every language you no longer need, then confirm with Tap on Delete. You can select several languages at once before deleting, so there is no need to repeat the process for each one.
Removing a language only clears it from the keyboard switcher. It does not affect your phone's system language, region format, or any text already typed in that language.
If a language reappears after a system update or app reinstall, it was likely added again automatically when a new app requested that input method. In that case, repeat the steps above.