Unused Amazon AWS Elastic Network Interfaces should be deleted in order to adhere to best practices and to avoid reaching the service limit. An AWS Elastic Network Interface (ENI) is termed as unused when it is not attached to any EC2 instance.
1. Sign in to the AWS Management Console.
2. Navigate to AWS EC2 dashboard.
3. In the left navigation panel, under NETWORK & SECURITYsection, click Network Interfaces.
4. Select the AWS ENI that you want to remove.
5. Click the Delete button from the dashboard top menu to initiate the removal process.
6. Inside the Delete Network Interface dialog box, review the resource details one more time, then click Yes, Delete to confirm the action. If successful, the selected AWS Elastic Network Interface should be removed from the ENIs list.