I found a way!
In the reuse folder Layout creates a folder structure that includes folder with the same mane as the old model. I deleted them.
Then I deleted the _PCB folder sitting beside the pcb file. Then I opened the design, the component doesn't have a 3d model anymore so I could assign the new one and then save to library.
Layout also crashes 7-8 times in 10 when I open the 3d view. I have an SR open with no solution yet.
Mentor, please fix this software asap.
We paid for the upgrade, we paid for maintenance every year, we deserve better.