want to get rid of an old work email auto populated in "from"

I have 2 apple emails and an old work email that exist on my iphone as potential email addresses from which I can send emails. Unfortunately the old work one uses the 1st three letters of one of the apple ones I use, so it's easy to inadvertently use my old work email. I can't figure out how to delete the old work email so that I'm unable to select it as a "from" email address. Has anyone found a way to address this issue?