default void removeFromParent() {
        getParent().getOurChildren().remove(this);
        setParent(null);
        getSubTree(n -> true).forEach(n -> n.setRoot(null));
    }
Removes this node and its subtree from the tree graph. This node's parent is set to null,
and the root node is set to null of all nodes in the subtree.
core/src/main/java/mrtjp/projectred/redui/RedUINode.java