Hi @ManojBhosale,
Can you explain a bit more about what you're trying to do? The account_id is an internal identifier assigned by Canvas to a specific account/subaccount (not a user account, that's completely different). A somewhat simplified hierarchy is that enrollments tie to sections, sections tie to a course, a course ties to an account, an account ties to another account up to the root account for the school institution. Users would generally be considered to be associated with the root account. With all this being said, an account_id really isn't something you would generate. The only time you'd have a new account_id is if you create a new subaccount.
If you can tell us the goals you're trying to achieve it'll probably help one of us to guide you on the best direction to take, which APIs you'd need to use, etc.
-Chris