Winger Low will now embark on a career in law and the 33-year-old is expected to combine that with part-time football after four years at Whaddon Road.
Youth product Lewis, who enjoyed a spell in the first team during the 2008/09 campaign, will also leave having struggling to force his way into Mark Yates' plans.
Smikle featured in every match during the 2010/11 campaign but he failed to force his way into the side during his second season with the club and he too is set to depart.
Young left-back Andrew is under contract until the end of next season but he has been told he can find another club.
Scott Brown, Alan Bennett, Steve Elliott, Keith Lowe, Harry Hooman, Bagasan Graham, Luke Summerfield and Jeff Goulding have been offered new deals.