Hi @shashanks445952 ,
This workflow logic will help you to solve your use case.

1) Query: Fetch all records from your table ( @id not equal to 0)
2) Dedupliction: select 'Generate complement' and in 'Edit configuration' select temporary schema and in next step add the expression to identify the duplicates. For example, if it is recipient schema, you can identify your duplicates by @email. So when you run the workflow, duplicates records will come in complement transition.
3) Split: Here you can add your filtering condition to filter last Modified 6 months ago.
4) Update data: Here you can delete or update those records as per your business logics.
Regards,
ParthaSarathy S