Hello Rakesh. 

As long as you have completed your 10th and 12th with a two year interval and complete all the other eligibilty criterias, you dont need a study certificate of class 6th. You can easily attend the certificate verification.

Here is a list of all the documents required for counselling through NEET UG-

• Mark Sheets
• 10th & 12th Passing Certificate
• NEET 2019 Admit Card
• NEET 2019 Rank Card/Rank Letter
• Category Certificate (If Applicable)
• Birth Certificate
• 8 Passport size photograph (Six)
• Identity Proof
• Provisional Allotment Letter