To build on Cynthia's remarks, I think its important to note that "any" project stakeholder may request a change request, but the project manager or the CCB will approve, postpone or reject the change. The Project Manager could be on the CCB as well. Often times, the Project Manager may not even have the knowledge or expertise to analyze a change request, that is why the CCB is so important.
You would have to refer to the Change Management Plan, a component of the Project Management Plan, to know who should submit a change request. The PMBOK guide page 88 stated that "Change Management Plan describes how the change requests throughout the project will be formally authorized and incorporated" and it also "describes the process for submitting, evaluating and implementing the change requests to the project" (page 525 of PMBOK). Any project stakeholder may request a change request but it may be the Project Manager or a CCB member or any assigned team member submitting the change request, in accordance to the Change Management Plan.