Long had been investigated by the Department of Homeland Security's internal watchdog past year over allegations that he inappropriately used government vehicles to travel to his home in North Carolina.
Federal Emergency Manager Agency administrator Brock Long said that it was time for him to "go home", according to Bloomberg reporter Jennifer Jacobs. His last day is March 8.
His deputy, Peter Gaynor, will serve as acting administrator.
In a statement, Long said FEMA had provided assistance on "more than 200 declared disasters" and thanked President Donald Trump, Vice President Mike Pence and Homeland Security Secretary Kirstjen Nielsen, whom he said "have been extremely supportive of me, the FEMA workforce and our mission". "I appreciate his tireless dedication to FEMA and his commitment to fostering a culture of preparedness across the nation".
President Donald Trump reportedly considered firing Long because of this in the days before Hurricane Florence slammed into the North Carolina coast in September. Homeland Security officials said there had been a longstanding practice of FEMA administrators using government vehicles to ensure they could remain connected during a crisis. Long's improper use of government resources for personal travel fit a pattern among senior Trump administration officials. It said this cost taxpayers $94,000 in staff salary, $55,000 in travel expenses and $2,000 in vehicle maintenance.
Long said he accepted full responsibility for the unauthorized use of the vehicles.
A former state emergency management director in Alabama, Long was faced with immediate challenges in the federal post, including Hurricanes Harvey in Texas and Maria in Puerto Rico. Elizabeth Warren (D-Mass.) have continued to call for an investigation into FEMA's handling of the Hurricane Maria disaster in 2017 and why thousands died in the wake of the storm.