The competition’s organisers said the tweet was “unacceptable” and confirmed their decision to dismiss her, just hours after she won.
Ms Esen has since said, via Instagram, that she was not being political.
The tweet was posted around the first anniversary of the 15 July coup attempt, when nearly 250 people died fighting an army uprising.
She wrote: “I am having my period this morning to celebrate the July 15 martyrs’ day. I am celebrating the day by bleeding a representation of our martyrs’ blood.”
Turkish President Recep Tayyip Erdogan regularly refers to the “martyrs” who died resisting the coup.
The beauty pageant’s organisers said the tweet did not come to light until after Thursday’s ceremony in Istanbul, after which they held a long meeting to discuss the situation and verify the post.
On Friday, they released a statement to announce their decision to rescind her title: “We regret to say that this tweet has been tweeted by Itir Esen. It is not possible for the Miss Turkey Organisation to promote such a post, when it aims to introduce Turkey to the world and contribute to its image.”
Ms Esen later responded with her own statement on social media: “I want to say that as a 18-year-old girl, I had no political aims while sharing this post.”