Premiere processing "byproduct" files erasable?
 

Over the course of the past 7 months or so I have closing on 200 gigs of internal HD space consumed and occupied by what I call aftermath/byproduct or were otherwise created during the post production process using that application.

I'm specifically referring to:

a) media cache files
b) pro auto save files
c) pro preview files

and the like!

What I don't want to do is to intentionally delete files that I may have to regenerate once more because some of that data points/links to live open projects that are not completed yet.

So, are any of these "safely" deletable so I can clear some hard drive space?

For example: is there any time lost, damage done or considerations if I did away with the media cache files?

What function do they have & should they be kept?

What I don’t want to revisit is spending/wasting hours tying down the computer re-rendering projects which would take hours for each case.