You cannot remove the Current User and the Default_User.
Before you remove a user, you must switch to a different user and exit the program. This will ensure the database connection to that user is closed (the database can connect to multiple users at the same time). Otherwise, the removal will not be done correctly.
Switch away from the user you want to remove > Exit VocabularyShop program > Launch the program again > click Setting menu > choose User Account > click Remove User
The Remove User dialog box pops up > click the drop down menu and select user you want remove > click OK
The Confirm Remove User dialog box pops up > click Yes
The user is removed.