You can make as many trees in your account as you'd like, but there's not built in mechanism to click somewhere and have it take you to a new family tree.
You could put a link to the new family tree in any number of the available fields (email, website, interests, activities...). But if you display those fields, they are not links in the tree itself. They are links in the left panel, so you could put the link to the new tree in, for instance, website, and put a Bio Notes entry to the effect: "See website link for complete family tree".