What command would you use to disable an active account for a former employee?

Using the command to disable an active account for a former employee leverages the '-L' option with the usermod command in Linux. The '-L' option locks the specified user account, effectively preventing the user from logging in. When this command is executed, it modifies the user's account status by disabling their password, thus prohibiting any access with their old credentials.

This action is a standard security practice when dealing with former employees, as it helps to mitigate unauthorized access to sensitive data or systems while still retaining the user account for potential records or auditing purposes. In contrast, the other options perform different functions that do not directly disable the account, such as changing the home directory, user ID, or username, which do not provide immediate security against account access.