I wrote about this about a year ago. There still hasnt been a fix for it that I can find. Deleting a learned word through the keyboard it's self doesn't seem to work. The word always comes back. Does anyone know of a fix for this?
Does the Samsung keyboard have a personal dictionary? If it does, your learned/saved words should be in there and you should be able to delete them. This is why I like G-Board it does have a dictionary that I can access and edit.
