Change username for paid accounts

Good Evening--

My name is Lindsey and I am a representative of Ultra4 Racing. This is the JotForm account our old communications manager set up using her name as a username and now that she is no longer with the company, we would like to change the username to reflect the company. Please let me know how I can go about changing the username. 

Thank You, 

Lindsey Fisher

Ultra4 Racing (Ultra4Racing.com)