Dear …
RE: Employment Termination
Effective immediately, your position with __(name of organization)__ is terminated. You are required to leave your __(station/desk/etc.)__ immediately. Arrangements to retrieve any personal belongings located on these premises, will be made with you at a later date.
Insubordination is the reason for your employment termination with __(name of organization)__. The documented incident that occurred with you on __(date)__ is classified as unacceptable. This type of employee behavior has never been and will never be tolerated at __(name of organization)__.
Enclosed, you will find all the appropriate employment termination documentation and your final pay.
Yours truly,