You have two choices. 1. You can create a persona. These people don't know you or anything about you. Create someone in your head who doesn't stutter, speaks with great confidence, and is an amazing salesperson. 2. Be you. A human who has a speech impediment. Someone who tries their hardest and that should be good enough for people getting trees cut by the power company. I guess a third option would be to quit, but that's for losers.