Can you change my username?

Yes, we can change your username for you. Simply give us the username that you would like to have and we will change it for you accordingly. You can also give other alternatives just in case your first choice is taken. I will wait for your response.

Can you please change it to Transcend.
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It appears that the username Transcend has already been taken. Perhaps you can give us an alternative username that you would like to have as your new username? I will wait for your reply.

Transcendmarketing
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As per your request I have changed your username from kal12345 to Transcendmarketing. If you require any additional assistance, please let us know.

Is there a way to change guest user to something else? And is there way to remove create your form today! On the bottom right?
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Guest user accounts needs to be registered in order to change the username.  Register the account using the same email address used to create the Guest account forms and select the username you'd like while registering. 

I believe you are referring to the email notification footer.  That can be removed by editing your email notification contents:

http://www.jotform.com/help/25-Setting-Up-Email-Notifications