It should be easy. But it's not. It appears to be attached from the bottom. Anyone know what to do?

 

It slides out from the bottom, see the right side of this pic

 

Based on the picture, it looks like it should slide out toward the fender. I have it drained and the two hoses released. But I can't get it to slide out. It seems looser the opposite way but there's a big bar there.

 

The workshop manual says to remove the cross brace that you refer to. To do that you need to remove the plastic windscreen cowl, which means removing the wiper arms. The expansion tank then slides towards the engine.

 

Only the brace needs to be loosened enough to slide the tank out easily, I've done mine. Nothing else needs to be removed.