When you take your iPad out of the box, you will notice that Apple has applied its own "signature" as per your email sent. To customize it your way, here's a guide to changing it.
Step 1. Go to "Settings" on iPad
Step 2. Select "Mail"> "Contacts"> "Calendar" from the sidebar
Step 3. Click on the Signature option
Step 4. Clear the default message
Either leave this field blank or add your own message.