What if I allow upload attachment but disallow delete?

Then use Record rules set ir_attachment table set create, read, write check and delete options uncheck.

Hi prakash, I could not find any record for attachment. Kindly refer to the screenshot. https://dl.dropboxusercontent.com/u/42025188/could_not_find_attach_record.png

create new group ex: Attachment/User and in the Access Rights tab add new item object name ir.attachment and check access right read, write, create and uncheck delete and group assign to the user.