I agree with super_camper. We had ours for sale and continued to use it. Luckily when it sold the new owner gave me 4 days to deliver it.
If you're not using it then it would be best to empty it. We filled a single car garage with everything we took out and sorted through it before we put it in the one we bought. We only put about half of the "stuff" back in the new one that we had accumulated in the old one.