Yes, you can. You can't change the URL, or PermaLink (web link name, in the format http:Hubbername.HubPages.com/hubs/hub-title-with-dashes.) That is locked down. But you can change the visible title of the hub, and it's easy. Just go into Edit Mode and click on the title. Make the change, then click away from the title.
I've checked with HubPages staff, and there is no need to change the URL (permalink), it is not significant to search engines.
It's a good thing that we can change titles. As we learn more about SEO, a better title can move us up in the natural Google page. Also, I misspelled a title once, and got to fix it!