To delete files that are stored in your Acrobat.com online account, please log in to https://cloud.acrobat.com and click the Files tab. You'll find your files in the either the Recent Files list or Document Cloud Files lists. Select the file or files that you want to delete, and then click Delete at the top of the file list.
I am in adobe acrobat.com when I open PDF attachments the go to a PDF file when I raise the file and right click it or try to edit it I don't have the option to delete it.