The big one is 24mm. You can use a 1 inch socket too since one inch equals 245 milimeters so it would only be .5mm off.
The smaller one is 22mm and you only need to remove it if you are replacing the spring. To remove the bracket just remove the 24mm big bolt. The small one at the top is just a stud to hold the bracket in it proper place when you tighten it down.
Be sure to get a new rubber O ring for the back of the bracket when you remove it.