A statement posted on the club's formal internet site on Friday evening confirmed the parting of techniques.
McDermott's long term at Elland Street had seemed progressively uncertain subsequent Massimo Cellino's takeover of the Yorkshire club previously this year.
In a assertion, Cellino explained : "Brian is a great manager and a wonderful male. He has been unfortunate to perform in these challenging circumstances.
"I did not thoroughly fully grasp the mess he had to work in, and the broken claims he had to deal with, right up until I have acquired associated hoping to change Leeds about.
"He has been a gentleman to deal with in our conversations and has been quite understanding of my wish to implement a new structure. His primary concern and precedence at all occasions has been the welfare and protection of Leeds United.
"I would like him very well for the future where I am positive he will keep on to have far more good results and thank him for his endeavours in becoming a stabilising and unifying figure guiding the scenes in incredibly challenging situation.
"His sincere attempts to information us to the safety of mid- desk when confronted with quite a few difficulties is appreciated by us all. He will usually be a good friend of Leeds United."
In the very same assertion, McDermott explained : "It has been my good privilege to take care of this excellent club and I have liked the challenge immensely.
" Nevertheless it is clear that Massimo wishes to put into practice a new construction and feels he will work additional effectively for Leeds with a mentor fairly than a supervisor.
"I regard that Massimo have to be totally supported in placing collectively his eyesight for the club so he can provide us the success we all want. It is my perception that when definitely United we are more robust.
"Massimo wishes to provide a new power to the club so that we can return to where we belong as a nutritious soccer club.
"To my players for their attempts I say a huge thank-you. To all the staff members and specially my excellent assistant supervisor Nigel Gibbs and my fantastic pal Patrick Dolan I am specially grateful for their assistance.
" Lastly to the outstanding drive that is the Leeds United supporters, I provide my heartfelt many thanks.
"Your help of me and the players was constantly an inspiration and I urge all people to get powering the workforce and the new operator following year to get us again to where we will need to be, preventing for trophies and competing at the prime - table of English and European football.
"It would not be straightforward, but Marching On Jointly we can get there.
"I want Massimo and all my pals at Elland Road every results in the foreseeable future."
McDermott leaves Leeds following guiding them to fifteenth position in the Championship in the 2013- fourteen time.