Delete muted users data files

**Is your feature request related to a problem? Please describe.**
I know that there still are the content of the guy who I muted in zeronet in my PC, although I cannot see them. But you know that it's dangerous when the illegal content that is published by the guys who I muted still lives in my PC.

**Describe the solution you'd like**
I know it is difficult to delete the text content of the muted guy because that would break the integrity of zites. However, in concept, it is possible to delete all the downloaded optional files of those muted guy and never help them distribute new optional files of those muted guy in all my served zites.