Go to Account Settings > Room Settings > Room Name to see your room url. You can then change it by clicking the field and typing the new name. Then hit the Save button.
Before you change the name of your room it is important to know what effects this will have.
If you've given your personalized URL out to any of your patients they won't be able to reach you at the old URL anymore. And if someone else happens to take the name, then your patient might end up in the waiting room of someone else!