He will remain in position until spring 2021 while the shopping centre developer looks for a replacement.
“The current environment, exacerbated by the impact of Covid 19, is undoubtedly the most challenging we have faced as a business,” Atkins commented.
“I feel now is the right time to search for a new chief executive, a person who can not only lead the business as we emerge from this period, but also into its next chapter.”
The firm, which has been hit hard by the coronavirus crisis due to its focus on retail locations, saw a £400mln sale collapsing last month after the buyer pulled out.
Shares, which plunged by over 60% in the past three months, rose 4% to 77.3p on Wednesday at the opening bell.