Hoarding can be dangerous. It possess health and fire hazard, and can make house unsafe. I know two separate incidents when hoarders killed due their impulsion several other people and they never faced even criminal charges. Many years ago, there were hoarding couple in my hometown well known for patrolling all dumpsters and filled their house from basement to roof with trash. They never threw even a newspaper. Once they managed to break to chemical waste dumpster, and brought several containers with unknown chemical in it in to their house. Chemical reaction cause a huge explosion that was seen from every part of the city. They lived in medieval center of the town and they destroyed the house. One firefighter, a my friend, died on the scene. Due unknown number of chemicals in the house, the military had to tear down the house. There was empty lot for years. Both received fines, but not a single day in jail. Another time, an elderly woman collected newspapers and cardboard that filled her apartment to ceiling. There was only narrow corridor to get through. Short curcuit set the place on fire. She survived, but woman living above her burned to death.
The best way to go through staff, and regularly throw items away. Put them by the curb, sell them on ebay, donate them, set them on fire on your backyard.