Sydney has made a further three changes to its list following the grand final loss to the Western Bulldogs earlier this month.
“We would like to thank Xavier, Jack and Abaina for the contribution they made to the Club,” Sydney head of football Tom Harley said.
“All three players worked tirelessly while at the Swans and should be proud of their efforts.
“We wish Xavier, Jack and Abaina all the best for the future.”
Richards played 12 games for the Swans in four season, including this year’s grand final.
Hiscox played one senior match for the Swans, while Davis failed to make a senior appearance for the club.