Hi S.Gautam,
From your description, you want to set up an alert on document deletion from a particular folder in a SharePoint 2010 library. Is it right?
You can open the library, and select the particular folder, then click Library->Documents->Alert Me->Set alert on this document. In the “Change Type” section, select “Items are deleted”.
Like the screenshot:

When a document from the folder is deleted, you will get an email like:

Best Regards,
Wendy
Wendy Li
TechNet Community Support
