Simply replace the unfilled areas such as "" and "[date]" with your information.
I would like you to think of our discussions on [date(s)] where you were notified of certain problems in your performance as an employee of our organization. Those identified problems appear to continue. Make no mistake about it, [name], [I/we/Company Name] [am/are/is] taking this very seriously and will not tolerate anything like this any longer.
Please allow this to serve as your final warning that [any further violations of company policy on your behalf / if you continue to fail to perform in accordance with our company standards], it shall result in your immediate dismissal without further warning.
__________________________ (Supervisor's Name) ______________ (Signature Date)
__________________________ (Employee's Name) ______________ (Signature Date)