Removing seized rounded power steering lines

Welcome to the wonderful world of corroded parts, LOL. As it is already rounded you are going to be limited in what you can do. However as a first step I would clean up as much of the fluid as you can, then stuff a bolt or even a dowel into the tube you cut off to lower the amount of fluid exposed to the next step. Then use a propane torch to heat up the pump casting around the fitting, not red hot, you just need enough heat to soften the glue and rust. Many of these lines had loctite on them from the factory and a bit of heat will soften that and let them free. Just have an extinguisher handy just in case. Now as to the wrench needed, Get a pair of vice grips with the curved jaws. Attach those as tight as possible to the flare nut fitting the tube goes into, the other reason for the bolt in the tube is as reinforcement so this step doesn't crush the fitting as you try to remove it. Heat the casting so it is just warm, clamp the vice grips on and tap them with a soft hammer like rubber or nylon. The idea with those materials is that they will deform slightly and not possibly cause damage to the pump. Good luck.