Is this user a clerk as well? Please check under HR management, Manage Clerk.
Do not check on his name again in the Manage Clerk; otherwise system will send a reminder to change his password every day. Manage Clerk, this setting is only meant for managing other employees' leave applications and not himself.
If this employee is not required to do any leave application on behalf of anyone (other employees), then please proceed to Delete in the Manage Clerk.