SQL Server Agent Job – Exists then Drop?

Try something like this:

DECLARE @jobId binary(16)

SELECT @jobId = job_id FROM msdb.dbo.sysjobs WHERE (name = N'Name of Your Job')
IF (@jobId IS NOT NULL)
BEGIN
    EXEC msdb.dbo.sp_delete_job @jobId
END

DECLARE @ReturnCode int
EXEC @ReturnCode =  msdb.dbo.sp_add_job @job_name=N'Name of Your Job'

Best to read the docs on all the parameters required for ‘sp_add_job’ and ‘sp_delete_job’