Hello, and welcome to our forum community.
There is one more bolt that you have to remove, it is called a 'stopper bolt' and it is located towards the forward end of the brake caliper assembly. See the picture that Joe (
@Mellow ) has posted directly above - the bolt with the socket wrench on it.
Here are links to two other discussions that contain information that I think will help you solve your problem:
ST 1300 Rear Caliper Removal and also
ST 1300 Rear Wheel Quick Guide
Michael
PS: Be aware that the bolt shown in the picture above is a
very safety-critical bolt. This means that when you remove it, you should inspect it for any possible damage or deformation, and when you replace it, you need to be sure it is torqued correctly to 69 N·m. Honda actually recommends that this bolt be replaced with a new bolt every time it is removed, but if you choose to not replace it, it would be wise to put some thread-locking compound on the threads of the bolt before re-installing it.