Cole started his career at the east London club and returned for a second spell in January, but failed to claim a regular starting role.
Fellow midfielder Collison also came through the academy ranks, making his debut in 2007, although his first-team opportunities were restricted by a persistent knee problem.
The Welshman was loaned out to Wigan last season and manager Sam Allardyce has allowed him to find regular football elsewhere.
McCartney, an experienced full-back, rejoined the club on a free transfer in the summer of 2012 and supplied cover at centre-back last season.
The 33-year-old, who had an early spell with West Ham, will cut his ties with the team when his contract expires.
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