Certified GKH Gardening Expert
Hardy hibiscus can usually survive winter outdoors but in cooler regions will need additional protection, such as mulch and wrapping. Therefore, you don't need to dig it up, unless you want to. As long as you can give it added protection during extreme freezing conditions (and as long as you don't have the tropical type, which needs to be inside over winter), it should be ok. The articles above will help.
Here are some options for winter protections: https://www.gardeningknowhow.com/plant-problems/environmental/protecting-plants-winter.htm