Hi Huma,
If you are looking for a sample relieving letter then please use the search tab given in this page. Again if you are looking for a specific letter for termination, then I would suggest you not to mention the same in their experience or relieving letter, as that does not look good in their career length or history. Some companies do issue the same reason while exiting. If you have provision, not to mention the same then that would be appreciative, though the employees have not completed their probation period.
You have mentioned that they did not follow the company policy. This does not make us understand the specific reason. Please find below some reason wherein the company does not consider anything, for not to provide the actual reason for discharge or termination, both sides.
Falsifying or withholding information on your employment application that did or would have affected company’s decision to hire you (this conduct will result in your immediate termination)
Insubordination
Refusing to work reasonable overtime; at times for project deliverables, etc
Negligence in the performance of duties likely to cause or actually causing personal injury or property damage, etc
Fighting, arguing or attempting to injure another;
Destroying or willfully damaging the personal property of another, including company’s property
Breach of confidentiality
Using or appearing to use for personal gain any information obtained on the job
Using Impelsys property or services for personal gain or taking, removing or disposing of company's material, supplies or equipment without proper authority
Gambling in any form on company's property;
Dishonesty & Theft
The possession, use, sale or being under the influence of drugs or other controlled substances during working hours or on the company's premises
Carrying or possessing firearms or weapons on Company's property
Unauthorized absence from work without proper notice and engaging in discriminatory or abusive behavior, including sexual harassment.