According to the club's social media posts on Sunday, they will be saying goodbye to seven players and team manager Herman van Dijkone whose contracts expire on June 30.
The 21-year-old Vietnamese player, whose contract expires on the same day, is not in the list.
Vo Le Trung, general director of T&T Sports Joint Stock Company and owner of Hanoi FC, which loaned the player to Heerenveen, said last Friday that both sides are still in talks about Hau's contract.
The Vietnamese left-back has only played for four minutes for the main team.
Since arriving in the country last September he has mainly been playing for the club’s youth team, Jong Heerenveen.
For the past three months all Dutch football leagues have been interrupted by the Covid-19 outbreak.