The midfielder has left the club for Tottenham in a big money deal that has shocked Elland Road supporters.
The 18-year-old is a lifelong fan of the club, while his father and grandfather also played for Leeds.
"Understanding the attraction of Premier League and European football, the club, with a heavy heart, agreed the transfer, but the move has strengthened the board's resolve to ultimately return Leeds to a position where it can meet the footballing ambitions of even its brightest stars," Leeds said.
"Whilst we understand that supporters will be hugely disappointed to lose such a home-grown talent, and a family name so synonymous with Leeds United, the move improves the club's chance to compete for automatic promotion next season by increasing our ability to build a competitive squad within the league's financial control regulations.
"Everyone at Leeds United is heartbroken to see one of our own depart and would like to thank Archie for all his efforts and professionalism.
“He leaves with the very best wishes for his future career and in the knowledge that Leeds will always be his home."