title: How to `pulumi destroy` RDS subnet group which is used by a RDS instance?
body: <p>I have RDS Subnet Group and RDS instance resources in my <code>index.ts</code>.</p>
  <pre><code>...
  
  // Create RDS subnet group
  const rdsSubnetGroup = new aws.rds.SubnetGroup(&quot;rds-subnet-group&quot;, {
    subnetIds: vpc.privateSubnetIds,
  });
  
  // Create RDS instance, MySQL
  const rdsMySql = new aws.rds.Instance(&quot;rds-mysql&quot;, {
    engine: &quot;mysql&quot;,
    ...
    // For a VPC cluster, you will also need the following:
    dbSubnetGroupName: rdsSubnetGroup.id,
    vpcSecurityGroupIds: [ec2SecurityGroup.id],
  });
  
  ...
  </code></pre>
  <p>It throws the error below when I <code>pulumi destroy</code>:</p>
  <pre class="lang-bash prettyprint-override"><code>Destroying (staging):
       Type                    Name                    Status                  Info
       pulumi:pulumi:Stack     myapp-infra-staging  **failed**              1 error
   -   └─ aws:rds:SubnetGroup  rds-subnet-group        **deleting failed**     1 error
  
  Diagnostics:
    aws:rds:SubnetGroup (rds-subnet-group):
      error: deleting urn:pulumi:staging::myapp-infra::aws:rds/subnetGroup:SubnetGroup::rds-subnet-group: 1 error occurred:
          * deleting RDS Subnet Group (rds-subnet-group-84e29cf): InvalidDBSubnetGroupStateFault: Cannot delete the subnet group 'rds-subnet-group-84e29cf' because at least one database instance: myapp-staging is still using it.
          status code: 400, request id: 2d691633-f9eb-4bf9-969c-f4db4ac4ee89
  
    pulumi:pulumi:Stack (myapp-infra-staging):
      error: update failed
  </code></pre>
  <p>Please help, how do I destroy my stack?</p>