"Don't mind me, just cleaning graffiti off a UNESCO world heritage site!" the volunteer, Anna Lois Taylor, wrote alongside the photo.
"I feel physically sick after every clean but this area makes me feel so much worse. It's horrific."
The photo shows Ms Taylor working to remove all traces of Milam's name.
Milam, 24, told the Dorset Echo she "felt awful" about having defaced the precious landmark.
"I feel awful because of this horrific event in my life and I wish to express my deep regret for the damage by my name written on the Jurassic Coast," she said.
"I have learned a huge lesson, one which will forever mark me. I reached back to the community to meet all the people who sacrificed their precious time to fix this disaster.
"I want to spread the awareness to everyone who doesn't understand the beauty and importance of this place. I am disappointed that I didn't understand it at the time and I don't want anyone else making the same mistake."
Milam said she would donate £30, or about $A55, each month to a local conservation fundraiser.
"Maybe nothing will undo the damage the writing caused but I will try to make things better and I hope people will give me the chance," the influencer added.
After every weekend, teams of volunteers spend hours cleaning the cliffs and removing bags of rubbish left by visitors at the popular spot, said James Weld, owner of the Lulworth Estate that owns the Durdle Door.
"It's constant," he told The Independent. "On Sunday morning we took about 50 bags and there was about 40 from Friday. It's horrendous.
"It is a natural environment and managing it is a complete nightmare. It's extraordinary how some people are behaving."
This is what we were doing this afternoon... in that heat!
Posted by Lulworth Rangers on Tuesday, 11 August 2020
