In the scenario you've described, the CEO, Margo Kettering, is faced with a web team that has excellent skills but is struggling with disagreements and missed deadlines. Among the roles listed, the one that is most likely responsible for resolving conflicts, ensuring communication, and meeting project timelines is the project manager.
Therefore, Margo is most likely to re-train or replace the project manager. The project manager plays a critical role in facilitating team dynamics, managing timelines, and ensuring that team members work cohesively, which seems to be lacking in this case.