If you are leaving Denmark for 6+ months you should read this omprehensive list of actions, that you should take before you depart.
When moving outside of Denmark or leaving for more than 6 months you must notify your local citizen service office (Borgerservice) and deregister your address, CPR card. You should also supply them with your new address abroad to receive any further information on your taxes.
Your social security status and rights will also change.
You may receive a tax refund on your vehicle when leaving Denmark – inform the tax authorities service (‘SKAT’). It may take 3 weeks to valuate your vehicle.
You must deregister your children from any institutions they are enrolled in one month in advance. This can be done by notifying the institution. If you require assistance because the site is in Danish you can go to the local citizenship service for help.