I stutter, and I teach at a university. You can do it. Accept your stutter, but also see if there are things you can do to alleviate the situation.  Also, it might be good to talk to the folks at the university to get a better idea what type of training you will have to do, how long will they be, etc. If they are short webinars, maybe you can practice and prepare them beforehand. Teaching isn't just about speaking.