If Sai Baba is considered the Supreme Brahman, why did he need to take a physical body and then leave it?

The scripture explains this as an act of grace for the benefit of his followers. Chapter 43 states that Sai Baba, who is the 'complete Supreme Brahman,' appeared in Shirdi with the 'sole desire for the welfare of devotees.' His physical manifestation was a result of the 'past merits of devotees,' taking a form to provide them with protection and guidance. Once this task was considered complete, he transitioned from his manifest form. The text describes this as him merging 'himself into the unmanifest,' returning to his 'previous unmanifest state.' Therefore, his taking a body and later leaving it was not due to the normal cycle of birth and death but was a deliberate part of his divine play, or 'lila,' undertaken for the salvation of his devotees.