As he joined a week's time before, please discuss with him and appraise him the situation and obtain resignation letter from him. However obviously he will expect either notice period or notice as per your employment terms which needs to be honoured.
Beyond certain years of experience, especially at senior levels getting a job will also become tough.
In the absence of knowledge of the terms of engagement of the employee, it is difficult to give an answer simpliciter.
The letter of recruitment given to the employee and accepted by him is an employment contract. Any termination of service will need to be seen in the light of the terms and conditions of his contract of appointment. It is normal to have a condition in the appointment letter that stipulates a probation period and also a rider that during the period of probation this contract can be terminated without giving a notice and also without giving any reason for terminating his employment. You may make use of this clause if it is present in the appointment letter. If not, you will have to give him a letter of termination giving him the agreed number of days notice as per his appointment letter failing which he would be entitled to claim salary for the shortfall in the notice period.
The ideal situation, however, would be to discuss his poor performance with him and about your intention to terminate his services as a consequence and request him to put in his papers for his own good and to avoid a blot in his CV.
Hope this helps
Before all this (if possible) the concerned authorities and management should give him a chance , discuss the issues and find a way out.May be he is misunderstood or the issues he is facing could be resolved by some help and assistance.
The background verification reports can also be checked on whether there has been any fraudulent or suspected fraudulent action in his experience records.
After all these efforts, then based on evidence of non-competency by the team manager, a discussion could be conducted.
I am 100% sure that it is not candidate fault.You hired one candidate having 15 years experience for your organisation . It totally pointing a interviewer who taken the interview & unable judge the candidates. So, this is my suggestion please rectify your problems..instead of pointing to candidates . I am 100% sure that, A person/ Panel who taken the interview not good at conceptual skill ..
Now you have no option left as the team manager does not want him. Ask the team manager to give the opinion in writing. Check the conditions in appointment letter issued to the employee. Terminate with notice, if candidate not willing to resign.
within 15 days,of his joining.