Only members with owner privileges for an organization or admin privileges for a repository can manage webhooks for an organization. For more information, see "Permission levels for an organization."
Chances are the account that you used to create the webhook token does not have Org Owner privileges in GitHub. Ensure that the account with which the token was created has these privileges. Use these credentials in the Jenkins Master Global configuration → GitHub Webhooks section and re-register the webhooks. Now, go to your repository and re-deliver the payload. This should fix the issue.
For help on configuring webhooks see About Webhooks in the GitHub Help documentation.
For help on building a webhook, including a full list of actions you can associate with, see "Webhooks" in the GitHub Developer documentation.