@ Dhananjoy, generally dusting with plain talcum powder repels flea beetles. You may use biopesticide spinosad (available in organic formulations) or fungal agents containing Beauveria bassiana and Metarhizium brunneum, which cause flea beetles to dry out and die. Otherwise, cover the rows to control it.
In addition, you must manage weeds properly and avoid proximity to other susceptible crops, because flea beetles can feed on them and the problem will persist.