Hi Leonnor, here's help I found for you.
Fill the water reservoir halfway with vinegar. Add water: Fill the reservoir the rest of the way with water. Run the machine: Start the brew cycle without inserting a K-cup. Repeat until reservoir is empty, discarding the mug contents after each brewing cycle
Janice, mine won’t run without a K-cup in it. How do I trick it?
Would you be able to use a used K-Cup that has been rinsed out? it's weird that it won't work without a K-Cup! Good luck!
Here you go: https://www.thekitchn.com/how-to-clean-a-keurig-cooking-lessons-from-the-kitchn-218103