If you do not generally allow employees to rescind their resignations, you do not have to allow this employee to continue working. Even if you have accepted an employee’s "change of mind" in the past, as long as you have legitimate job-related or business-related reasons for not allowing this employee to continue, you may treat him differently. For example, if you have already filled the position or reassigned the job duties to other employees, you can legitimately argue that there is no position available for the employee. Alternatively, if the employee’s performance has been less than stellar or you simply do not want him to continue working in your organization, you can explain to him that the organization’s policy is to treat resignations as final, except in certain, limited circumstances.