In the Unordered Maximum Tree Orientation problem, a set of paths in a tree and a parameter is given, and we want to orient the edges in the tree such that all but at most paths in become directed paths. This is a more difficult variant of a well-studied problem in computational biology where the directions of paths in are already given. We show that the parameterized complexity of the unordered version is between Edge Bipartization and Vertex Bipartization, and we give a characterization of orientable path sets in trees by forbidden substructures, which are cycles of a certain kind.