Dear Neha,
At the workplace, there are two types of communications, one is formal and another is informal. Both co-exist and are inseparable. Rumours are offshoot of informal communication.
As far as the case at hand is concerned, someone must have felt that person X has resigned from his job. However, feelings appear to be over-inflated and took the shape of a rumour. Like a bubble, this rumour started floating in the office.
You may circulate a mail stating that a rumour has been going round about person X's resignation. However, the person does not have any intention to quit the job. As a cautionary advice, write that employees should not rely on informal sources and neither should they pry on someone's resignation.
Lastly, about the quality of your English. It has spelling and grammar mistakes and hardly it befits a stature of manager. Therefore, before uploading your post, think of the general estimation that comes along with the designation. If you ignore the suggestion, it could be at your peril.
Thanks,
Dinesh Divekar