Secure file delete / move

Hi, I just installed cryptomator on my android/graphene phone. I wanted to secure the documents containing sensitive data.

I created the vault and copied the files there. My question is - what do I do with the files located in the folder I copied them from l (like downloads).

If I delete them, it will be probably possible to recover them. How to securely move (not just copy) the files to the vault? I assume it is not possible to download the files directly to the vault via the web browser?

Any recommendations how to tackle the problem?