Remove flex duct running from crawl space to attic in addition?

Repairing water damage in an home addition and discovered what looks to be a dryer vent hose connecting the crawl space to the attic. Is this need for venting? The attic and crawl space are connected to the rest of the house now but the attic was not connected when the addition was built.

This is in a climate that has high humidity in the summer and below zero conditions in the winter. It seems like this would be a place for moisture to condense and big heat loss in the winter.

My instinct says remove and insulate the spots well.