post https://apibeta.familysearch.org/platform/trees/
This post allows only one tree to be updated at a time. The treeId in the URL must match the id of the tree in the request body. You can modify the startingPersonId, hidden, private, name, description, ownerAccess and groupAccess fields using this POST operation. Passing an empty string for an attribute will remove the value for that attribute. Hidden can only be set to false.