Which argument in smbpasswd is best used to secure user accounts by removing them?

The argument in smbpasswd used to secure user accounts by removing them is the one that stands for the action of deleting or removing a user from the Samba database. When using smbpasswd, the option '-x' is specifically designed to delete a user account from the Samba password database. This action effectively prevents the specified user from accessing shared resources on the network, thereby enhancing the overall security of the environment by ensuring that former users cannot log in or access shared files.

In contrast, the other options serve different purposes. The argument '-d' disables a user account but does not remove it from the database, allowing for the possibility of re-enabling the account later. The option '-e' is used to enable an account that may have been previously disabled, while '-a' is for adding new users to the Samba password database. Understanding the functionality of these different options is crucial for managing user accounts effectively within Samba and maintaining security protocols.