How would you deal with a Top Performer who has an extremely negative attitude?

Top performers although are considered valuable assets to any organization; negative attitude can destruct more as it will have negative impact on more employees who will be dissatisfied.
Core employees or right employees should enjoy the right skills, knowledge and attitude and this employee is lacking an important cornerstone.
from my point of view such type of employees should be managed carefully for not having negative implications on the workforce; if you don't fix his attitude behavior he will spread the dissatisfaction among employees and I personally met such case.
Also, if you ask him to leave, most employees will not understand the reason as they consider him high performer and his leave spread the feeling of instability.
I believe the best way is to directly and immediately address the topic with the employee and document this as unofficial action for not to be considered warning letter and to be referred to in case required latter.
Allow time for change and reassess the change, if there is any change even if minor, start to engage him in more reforming programs that fix his negative attitude.
Yet if there is no improvement, I believe you should have a plan of his exiting.
It is very important that he first starts to improve his attitude as this reflect his willingness to change and that he is not resisting it.

I'll have a meeting with him and will point out my reservations.
Its important to have feedback from your team mates and this sort of situation arises when there is lack of communication.
From the feedback I get from the meeting, it will be easy to draw the course of action.
For me, a negative reinforcement has its own repercussions

I will arrange a meeting with him and clarify my concerns regarding his attitude, I will give him a chance to improve his performance but if he didn't will let him go.

Address the issue, convey the consequences which you fear and how it can effect your organization and team and the steps which become compulsory to be applied.
Guidance should always be positive and keep a close eye on the attitude.

negetive attitude, comes were in , your friend's and relatives , and parent's always talk negative of him, insted of positive.

To deal with it , is very simple , always talk to him , and appreciate his work, and try to motivate him , in doing better always, .