@Lars_Fischer Welcome tot he forum!
Currently, you’d have to go to the Web Vault, and select the “Clone” function (in the popup menu that appears by clicking the kebab icon):
On the “New Item” form for the cloned item, you will then be able to change the ownership from the organization to “My Vault”:
FYI, with the upcoming release of the redesigned browser extension UI, you will be able to do the above tasks directly in the browser extension.