Where is the signature setting on my Samsung Galaxy Mega?

At the bottom of all my text messages it has an annoying signature big in all caps everyone is always replying back to me why do you have that on you messages it confuses them. I have went all thru my phone trying to figure out how to get it off so if possible I need step by step instructions please please

Hello.

It should be like my Note 3. It's not in the main settings.

Open the Message app, then hit Menu and you should see it there hopefully.