Hardened polyurethane remover
The one solvent I see referenced the most for polyurethane foams is N-methyl-2-pyrrolidone or as the the cool kids call it: NMP. You don't have to just take my word for it a certain supplier that I have no affiliation with sells it for this purpose: Spray Foam Systems NMP.

As far as the purpose of ethanolamine, it must either be reacting to reduce chain length.  If you look at the urethane group below the Carbon bonded to two oxygens and a nitrogen is susceptible to attack by the basic ethanolamine. This reaction would break the molecular bonds making the polymer chains shorter and thus more mobile and more easily dissolved, thus saving time. This explination is a little hand-wavy but I didn't want to go deep into organic reaction mechanisms.