You can remove or change it, just log into your carrier's BIS and change it in your profile. Google turned up this for Verizon. h t t p://bis.na.blackberry.com/html?brand=vzw (Notice the spaces, I cannot post links with under 10 posts.)
Yes. You have to log into the Blackberry site and modify your email setting there.
I do not remember the url for that. I remember dealing with a different problem that required the Verion tech to call a BB tech and I posed that question while I was on the line with them.
You can do this from your BB. It's called a signature and you can remove it or change it. You'll have to access your carriers BIS site from your BB or PC. Edit the email account and look for signature.