How to cancel unregistered will deed through witness help ???

Such a Will is invalid and illegal document.

Consult a local prudent lawyer with relevant document for proper analyses and professional advise / required proceeding..

How to prove it invalid ???

It is advocates duty to prove it as invalid will you don't worry .

How you are concerned with the subject will i.e, what is your locus standi ?

I was cheated by brother through fake will deed , in court I ask court to cancel the registration of my brother and cousin only through os petition 

It is the duty of beneficiary to prove subject will in terms of Section 68 of Indian Evidence Act, 1872 which reads as:

Section 68 in The Indian Evidence Act, 1872

68. Proof of execution of document required by law to be attested.—

If a document is required by law to be attested, it shall not be used as evidence until one attesting witness at least has been called for the purpose of proving its execution, if there be an attesting witness alive, and subject to the process of the Court and capable of giving evidence:

Provided that it shall not be necessary to call an attesting witness in proof of the execution of any document, not being a Will, which has been registered in accordance with the provisions of the Indian Registration Act, 1908 (16 of 1908), unless its execution by the person by whom it purports to have been executed is specifically denied.

General proposition of law has been mentioned Under Section 68 Of Indian Evidence Act, 1872 which deals with ,”How a document which is required by law to be attested should be proved”

But regarding a Will, in order to prove it, requirements of Section 63 of Indian Succession Act, 1925 should be complied with, i.e. :

1. Establishment of the testamentary capacity of the testator.
2. Execution of will by testator
3. Signed by the testator with free will (consent).
4. At the time of signing it testator was of sound mind.
5. At that time he understood nature and effect of disposition.
6. Signing of Will was done inn presence of two witness or was personally acknowledged.
7. Examination of at least one witness in the court for proving its due execution.

The onus of proving will is on propounder { Savithri Vs. K. Amma}

Therefore, If the Will is invalid then as per above norms, Propounder won’t be able to prove it.

last will shall be valid even if unregistered.