I noticed that the branding is still at the bottom even though I remove the branding option.

Find attached a reply message Jotform sent to one of my client after he
submitted the jotform.I noticed that the branding is still at the bottom
even though I remove the branding option from the setting.Please I need
urgent help.

I'm assuming that you are referring to your autoresponse email body? The branding on that email can be removed by editing the email body.

Here's sample screencast:

I hope that helps. Let us know if you have any questions or if you need further assistance. 

Do I need to do that for each form?Or there is a way of doing it at once
and it applies to all forms I created.
...

It should be for each form, but it looks like a bug. Can you please try creating a new form and create a new autoresponse then let me know if the footer branding still appears on a new form?

Looking forward for your response.