code: public MockVpc deleteVpc(final String vpcId) {
         if (vpcId != null && allMockVpcInstances.containsKey(vpcId)) {
             return allMockVpcInstances.remove(vpcId);
         }
  
         return null;
      }
docs: Delete vpc.
  
  @param vpcId
  vpcId to be deleted
  @return Mock vpc.