Try changing it to
Do.Cmd.RunSQL "delete * from table1 where id in (select id from [table 2] where ENVRNMNT_STATUS = 'Prod' and RELEASE_FLAG= 'N')"
Unless that table is not called table 2 but is table2 in which case use
do.Cmd.RunSQL "delete * from table1 where id in (select id from table2 where ENVRNMNT_STATUS = 'Prod' and RELEASE_FLAG= 'N')"
Note the use of single-quotes in both cases