@PraveenShukla
You can use "Masquerading" to send API requests as another user instead of creating an access token for that user, this is useful when you wanted to perform an action on behalf of a user
https://canvas.instructure.com/doc/api/file.masquerading.html
However, if your account is an Admin, you can get data for any users without their API token.
If you're designing an app for users to utilise API, you will need to implement OAuth2, which requires a user to login to Canvas using their credentials then it will generate the necessary API token for the user to perform API requests.
https://canvas.instructure.com/doc/api/file.oauth.html