Open Outlook
Go to the folder where the sent message is located (usually Sent Items)
Double-click the message you want to recall to open it
Click the Message tab
Select Actions (or More options)
Choose Recall This Message
Choose whether to:
Delete unread copies of this message, or
Delete unread copies and replace with a new message
If replacing, open the new message and edit it as needed
Click OK
Confirm the recall request when prompted