If your security group is no longer required, you can delete it.
Figure 1 Default security group

Delete or modify the rule and delete the security group again.
For example, if the source of a rule in security group sg-B is set to sg-A, you need to delete or modify the rule in sg-B before deleting sg-A.
in the upper left corner and choose Network > Virtual Private Cloud.The Virtual Private Cloud page is displayed.
The security group list is displayed.
A confirmation dialog box is displayed.