The 25-goal top scorer, runner up in the Golden Boot race, has been released, the Clarets say.
The club’s Player of the Year, 28, won’t be short of offers for next season after a great season for the former Forest Green, Dagenham and Crawley finisher.
A Chelmsford statement read: “The striker joined us in the summer of 2018 following his release from League One outfit Gillingham, with a helping hand from the Supporters' Club 12th Man fund.
“He will be fondly remembered for his hat-trick in the Boxing Day 5-1 thrashing of Essex rivals Billericay Town at the Melbourne Community Stadium, including scoring the only goal of the game in the reverse fixture at the AGP Arena.
“Rhys also picked up Player of the Year, Players' Player of the Year and Away Player of the Year at the End of Season awards.
“We wish Rhys all the best for the future.”