He decided to step down due to some personal changes.

21-year-old, “milk technician” from Germany, refused the title of Mr Gay World that he has won in May this year.

Klaus Burkart
Personal changes made me unable to live up to the expectations and serve the community – thepurple.com

Explaining the reason to make such a decision, Klaus said that his “personal changes” made him unable to “live up to the expectations and serve the community.”

He announced about his resignation after the period of seven months by writing a letter on Mr Gay World website.

In his open letter Klaus explained: “When I entered the 2015 Mr Gay World competition in South Africa I thought that becoming Mr Gay World was the biggest challenge of my life.” He added, “Indeed it is very challenging and exciting winning the title, but what is more challenging is living up to the expectations, responsibilities and duties that come along with it.”

Klaus Burkart
Being the Mister Gay Man World and serve the LGBT community was my honor and pleasure – kitodiaries.wordpress.com

Klaus also said that he made this decision with “great sadness.” According to the rules of this competition, the owner of the second place takes the winning title. So, now Emmanuel Mass Luciano of Hong Kong became the owner of this title. “I know he will be a great representative for our community, who will put all his heart and passion into his reign,” Burkart added in conclusion.
“Being the Mister Gay Man World and serve the LGBT community was my honor and pleasure but unfortunately, due to changes in my personal life I am no longer able to continue to fulfill these responsibilities. With great sadness I report that I have to refuse the title Mr Gay World 2015 “.
Burkart announced about his decision on his Facebook page thanking the fans for all the support he got.