60 gigs in the cache folder – can I manually delete

Hello, I have inherited a website that is using wp fastest cache. I am running out of disk space because I have 60 gigs in the cache folder. I am not familiar with caching plugins, so I am not sure if I delete the files manually if that will cause issues. right now my concern is disk space.

#1 Can I manually delete any of the files under the cache folder?

#2 Below are the folders under wp-content/cache
Is this cache.bak folder part of wp fastest cache? I have a feeling someone before copied the folder, but I am not sure?

cache/
all
cache.bak
et
tmpWPFC

#3 Can I delete folders out of tmpWPFC ?

Any help is appreciated. Thank you.