Ripia, said to have a chronic gambling problem, was captured on CCTV taking money belonging to players in the changing rooms at the Force's Mount Claremont headquarters, the Sydney Morning Herald reported.
Force management were reportedly considering whether to tear up Ripia's contract or suspend him when the five-eighth offered his resignation.
The club yesterday confirmed it had agreed to accept the resignation.
In a statement, it said it had investigated a serious breach of team protocols.
"The club wishes to stress that the matter relates to an internal incident at the club and does not involve any member of the public or public property," it said.
Police had not been called so far because none of the victims had made a complaint outside the club.
Players had noticed missing money over several months and, while Ripia had been been suspected, he had denied it until he was told about Friday's CCTV footage.
Ripia, 26, had previously had counselling, arranged by the Force, for his gambling problem.
A spokesman for Ripia's management, Inside Running, did not wish to comment.
Ripia played for New Zealand Maori and NZ under-21s and under-19s.
He played three seasons at the Highlanders and was signed from the Hurricanes as the Force's 2011 overseas developing player.
However, his playing time was limited last year with multiple injuries and he took the field only seven times.
He had been set to play a bigger role this season after Wallaby James O'Connor's shift to the Melbourne Rebels.
