Sorry to say either you misunderstood or the salesperson didn't know what they were talking about.* Maybe they meant you can grow it outdoors in summer in a pot.* Chinese fan palm aka Livistona chinensis is only hardy to zones 9b to 11.* I too live in Maryland and it's not hardy here.* If you cut it back you will kill it by cutting off the growing tip.* You will need to dig it up, put it in a pot and bring it indoors.* This should be done before the night temps dip below 50*F, and best before you turn on the heat indoors.
Here's how to move plants indoors and outdoors.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.