Possibly a hacksaw or grinder....
The ball joints spin on the ends of the drop links..... Different brands have different solutions. They either have a keyed section to hold with a spanner at the bottom of the threads nearest the ball joint (this works!) or they have an allen key socket in the end of the threads (this doesn't work so well).
They go soft and rusty with age so the allen socket tends to rust up or turn to cheese when you try and use it. Couple that with the thread lock nuts that will be tight as a ducks bottom they're surprisingly awkward for a simple bit of metal.
Your best bet - give the threads a clean with a wire brush before you start and then add either penetrating oil or WD40 liberally to ease the process and see how far you can get. If you do it right and have a little bit of luck on your side you'll have them off. Otherwise you'll get half a dozen turns on it before something rounds out and you resort to the hack saw shortly followed by a hammer and chisel.