I have not read anything regarding this, but from what I understand, you cannot modify url once it is created. What you can do though, if you are desperate to have it changed, is to create a new hub with the url that you want. Then, copy previous content in the new hub. And then delete old hub (do not forget this or your new hub will be seen as duplicate content). It is a little bit of work, but it works if you really need it.