API remove inherited_ace

We are working on a self-service catalog for Isilon. One of our requests that creates a new SMB share also modifies the ACL of the directory that is created for the share. Currently the parent directory has Inheritance for its sub-directories turned on. Using the API, has anyone found a way to after creating the directory to disable inheriting permissions from its parent?

I can delete all the previous ACEs on the new directory through the API but when I apply new permission to its parent, they apply to the new directory. You can also see the "Include inheritable permissions from this object's parent" checked when you look at the Advanced Security Settings from Windows.

Here is some sample code PUT code which applies the MYDOMAIN\admins group and removes any existing inherited permissions; however, I can still see that parent inheritance is turned on.

{ 
"acl" : 
[
{ 
"accessrights" : [ "dir_gen_all" ],
"accesstype" : "allow",
"inherit_flags" : [ "object_inherit", "container_inherit" ],
"trustee" : 
{ 
"id" : "SID:S-1-5-21-1111111",
"name" : "MYDOMAIN\\admins",
"type" : "group"
}
}
],
"authoritative" : "acl"
}

Thanks.