How can I make the form one submission only?

Since you never provided more info on what you're trying to achieve, I'll just list some guides that will help you to limit Form Submissions:

1. How-to-Set-Unique-Submissions-on-a-Form

2. How-to-set-Form-Limits-Based-on-a-Unique-Question

3. How-to-limit-submissions-in-a-form

In case we misunderstood your question, just get back to us with a bit more info and a clearer description of what you're trying to do so we can better assist you.