An inmate's ability to block contact is more limited than most people assume, and they have zero control over their administrative information.
On the administrative side, inmates cannot change their name in the system or alter their booking number under any circumstances. Those designations are assigned by the jurisdiction at intake and are fixed. The facility controls that information entirely, and no inmate request changes it.
On communication, the picture is a little more nuanced. An inmate can request that a specific person be removed from their approved visitor list, which would block in-person visits. That is about the extent of their direct control. They cannot block incoming mail at the facility level, though they can choose not to respond to it. They cannot prevent someone from putting money on their account. They cannot block phone calls that come through the facility's system since they are the ones initiating all outgoing calls anyway.
If you are being blocked from visits specifically, that request came from him and was processed through the facility. You can contact the warden's office to ask about the visitation restriction, though facilities generally honor an inmate's request to remove someone from their list.
If your concern is that you simply cannot reach him and are not sure why, the more likely explanations are a phone restriction from a disciplinary issue, a facility lockdown, or a transfer rather than any active effort on his part to block contact. A call to the facility's counselor is the fastest way to get clarity on what is actually happening.