The Title of a payment form is displayed by default at the top of the form when the payer is checking out. You can choose to hide the title. To do so:
1) Click on the Themes button in your account's main navigation
2) Click on the Create New Theme button (or click on one of the themes you've already created)
3) Find the Form Title section and choose No to the "Display form title?" question
4) Click the Create Them or Update Theme button
5) Now, when you create or edit a payment form, you can apply this theme design to the form.