Hello HùngNguyễn13,
I'm John an Independent Advisor and a Microsoft user like you. I'll be happy to assist you today. I understand you want to remove languages in input method that still show up.
Please try this if it helps.
Press Start then search Powershell
Right Click then Run as administrator
Paste the command below then hit Enter:
$UserLanguage = New-WinUserLanguageList en-US
After that, Paste the command below then hit Enter:
Set-WinUserLanguageList $UserLanguage
Press Y then Exit Powershell
Restart your computer
After restart, English (United States) will be the only language under Preferred Languages. Kindly add Japanese language again.
After removing the extra keyboard languages, proceed to the procedures below
Open a Microsoft Office program such as Excel or Word
Click File > Options then select Language
Choose Editing Languages, Please check if you see other keyboard languages. Remove the extra keyboard languages.
Restart your PC
If not, proceed with the method below
Press Start then search control panel
Click Region > Administrative tab > Copy settings
Make sure English United States is set to all categories under Current User.
On the bottom, Check both options "Welcome screen and system accounts" and "New user accounts"
Click OK
Restart your PC
I hope this helps! Please let me know if you have any further concerns.
Sincerely,
John DeV
Independent Advisor