how do i delete network interface that its type is lambda

Hello.

I think it would be best to contact AWS Support as output in the message.
In this case, there may be a problem with your account, so I think you should open a case with "Account and billing" and inquire.
Inquiries under "Account and billing" can be made free of charge.
https://docs.aws.amazon.com/awssupport/latest/user/case-management.html

It appears that you've utilized a script to attempt to identify why the ENI associated with Lambda hasn't been automatically deleted. Since you've confirmed there are no Lambda functions or versions using the same subnet and security groups as the ENI, and you've already attempted to delete it manually but couldn't be due to the type being Lambda, here are a few additional steps you can take:

• Verify Dependency: Check if there are any other AWS services or resources that might be indirectly associated with Lambda, which could be utilizing this ENI.

• Inspect CloudWatch Metrics: Look into CloudWatch metrics to see if there's any activity or usage associated with this Lambda-related ENI.

• Check AWS Config Rules: Review AWS Config Rules to ensure there are no specific rules or configurations that might be linked to Lambda and causing the ENI to persist.

• Examine CloudFormation Stacks: Investigate if any CloudFormation stacks might have created this ENI, even indirectly through nested stacks or dependencies.

• Consult AWS Documentation: Refer to the latest AWS documentation for any updates or known issues regarding Lambda-related ENIs.

• Contact AWS Support: If none of the above steps yield a solution, reaching out to AWS Support with detailed information about the issue, including the output of your diagnostic script, will likely provide the best assistance.

Remember to approach deletion with caution, especially when dealing with network interfaces that may have dependencies or implications on your infrastructure's functionality.