Error deleting VPC / Subnet / Network Interface

Hello!

After completing some more tutorials (mostly about Kubernetes) I tried to clean up everything I created. A CloudFormation Stack resisted deletion though - I tried multiple times, in the end opting to skip some resources to get rid of it. The stack is now gone. (I did delete two stacks and the EKS cluster simultaneously, that's the only thing I did different compared to previous successful clean-ups)

Now there are some bits left that I'm unable to delete:
One VPC - says I need to delete the network interface first.
One (of three) subnets - says it contains one or more network interfaces.
One network interface - 'Detach' says I don't have permission to access the specified resource (???). Using the option '[x] force...' says the same.

Network interface ID: eni-0d0d851f513754b64
Subnet-ID: subnet-060bdfe7dd3f8804f
VPC ID: vpc-0bee6e5754575718c
Zone: eu-central-1b

What can I do to get rid of this stuff?

Thanks in advance,
Michael