The Form Links tab under General Settings enables you to set the URL that people use to access your form. The default link is usually the Event Name you entered first when you created the form (with no spaces) followed by the form number.
You would customize the URL to have a more clean, inviting, and professional link.
To do this, type in your new form link (without spaces) and click Add. Then, remove any old links that won't be used by clicking on the X on the very right of the same line.