I have a headset wrench for 4 different sized nuts hehe.
But yeah, vice grips work but will tear up the outside of the nuts. Channel locks also work.
Just go buy a wrench dude.
Table vice, leave the wheel on the fork, tighten the table vice around the top nut, and use your hands to unscrew it by holding the wheel. I think this way is alot easier than wrenches, just don't bend your fork.
lol just get a large adjustable wrench or channel lock. its not that expensive, it will last forever, and it can be used for just about everything. just make sure you get a good one shitty chinese-made tools are shitty.