You can only really get rid of attachments by deleting the e-mail. If you want to keep the text click on forward there is a link there which says Remove this attachment, click there and then send it to yourself. You can delete individual e-mails by clicking in the little boxes to the left, which selects them , then pressing delete. In All-New Mail if you click in the little box to the left of ‘From’ this selects all in Classic it just selects a page, then press delete and they all go.