According to a leading local website, eKantipur.com, the former princess, along with her three children, boarded a Silk Air flight to Singapore Thursday afternoon.
Police escorted Himani to Tribhuwan International Airport in the capital Kathmandu.
Former crown prince Paras Shah left Nepal on July 1 to find a good school for his children and home for his wife.
The former royal couple went to Singapore to admit their three children in to a school in Singapore.
The Constituent Assembly declared on May 28 that the country became a federal democratic republic.
