I would like a custom url.

i would like a custom url https://form.jotform.com/seawidedealerform

is this possible?

my number is 9518700333

You can follow our guide here https://www.jotform.com/help/261-How-to-Create-a-Custom-URL-of-a-Form on how to apply custom URL.

As for your change username request, I will be answering that on a separate thread here https://www.jotform.com/answers/1789439.