The average size of a cached page should be about 200-400Kb. That means if you have 1.000 pages the normal cache size will be about 200-400 Mb.
If cache size is larger than normal, it usually happens if there are a very large number of pages or if there is a dynamic part in JS or CSS – some themes/plugins creates dynamic js and that is why the folder is filled up.

Be sure to manually remove the entire contents of the cache folder and do the following steps:

1.) Enable Separate Styles and Separate Scripts in Optimization settings:

2.) Exclude unnecessary post types: autoconfig should find most and exclude them automatically but you can add them manually: Settings > Caching > Exceptions> Exclude Post Types

Afterwards rebuild the cache and see if the problem is solved.

If you still don’t have enough space for this you should maybe consider to exclude some pages from cache, or upgrade to a larger hosting package.