If you want to remove an attachment from an email message, right-click the attachment, and click Remove. You can also select the attachment and press Delete on your keyboard.
Delete a single attachment
Open the email that contains the attachment you want to delete.
In the Attached box, right-click the attachment, and click Remove.
Note: This method deletes only one attachment at a time.
Remove an attachment by using the Delete key
Click the file that you want to delete in the Attached box.
Press Delete on your keyboard to remove the attachment.
Notes: To delete multiple attachments at once, press and hold the Shift key on your keyboard. Click the first and last attachments in the series, and press the Delete key to delete them all.
To select multiple attachments in any order, press and hold the Ctrl key instead of Shift.
To select all of the attachments in an email, right-click in the Attached box. Choose Select All, and press the Delete key.