Deleting e‑mail messages that you no longer need can free up space on your hard disk and improve the performance of Windows Mail.
Open Windows Mail by clicking the Start button , clicking All Programs, and then clicking Windows Mail.
In the message list, click the message you want to delete.
To select multiple messages, hold down the CTRL key and click the messages you want to delete.
On the toolbar, click Delete.
When using a POP3 e‑mail account, deleted e‑mails are moved to the Deleted Items folder when you click Delete. To permanently remove deleted items from your computer, click the Deleted Items folder, click the Edit menu, and then click Empty 'Deleted Items' Folder.
When using an IMAP e‑mail account, deleted messages aren't actually removed from the message list when you click Delete. Instead, they appear with a strikethrough in the message list to indicate they're marked for deletion. To permanently remove messages that have been marked for deletion from your computer, click the Edit menu, and then click Purge Deleted Messages. After deleted messages have been purged, they can no longer be recovered. To undelete a message marked for deletion, click the message, click the Edit menu, and then click Undelete.
To automatically purge deleted messages from your IMAP e‑mail account, click the Tools menu, and then click Options. Click the Advanced tab, click Maintenance, and then click Purge Deleted Items when leaving IMAP folders.