To make your PDF un-editable to others (so you can email them or post them on social media), you’ll first have to convert it into an image.  The below videos will show you how to do that:

Email Your Flyers (from a PC) https://www.youtube.com/embed/uLkj6-J_co8?rel=0&showinfo=0

Email your Flyers (from a Mac) https://www.youtube.com/embed/SpAkllVR-0M?rel=0&showinfo=0