You can delete a VPC if the VPC is no longer required.
You can delete a VPC only if there are no resources in the VPC. If there are resources in the VPC, you must delete those resources before you can delete the VPC.
A VPC cannot be deleted if it contains subnets, Direct Connect connections, custom routes, VPC peering connections, or VPNs. To delete the VPC, you must first delete or disable the following resources.
If there are any EIPs or security groups, the last VPC cannot be deleted.