You'll want to remove the wheels and just start over with the assembly.
Some might try to leave the under carriage assembled and rotate it, but I would start over and deal with each leg separately.
To remove the wheels you need to deal with "push nuts"....Weber calls the "hubcaps".
I like to use two, opposing miniature pry bars and pry with each bar, simultaneously and with equal pressure.
In this way, the push nut will come off and be re-usable.
Here is a thread that has a pic of the bars that I use...
http://tvwbb.com/showthread.php?66659-Kettle-Wheel-Upgrade
After you get the wheels off, the "triangle" comes off next and then the legs.
The legs are simply "pushed on" and held in via a nub in the socket that bites into the leg.
A press fit....lightly tap the legs into place with a soft hammer (or similar).
"Soft hammer" means a dead-blow hammer, a rubber mallet, or at least cushion the hammer blows with a piece of softwood.
Getting the hubcaps off is a simple task with the right tools.
It can be a PITA though, if trying to use a single, flat bladed screwdriver.