I have the previous version of Komplete and I've purchased enough 3rd party libraries I have to consider what I really don't need to free up space. The nice thing is if you remove some libraries you can download them again.
Always wondering what other users have removed.
I removed
Most of the Abbey Road Drums - got enough drum sets with XLN, Toontrack
Symphony Essentials - except woodwind, percussion.
??? to remove
Not sure Session Strings Pro 2 is needed. Bot enough strings
All Scarbee libraries except guitar
Of course when you go through these you think "oh maybe I should keep it installed".
As for pianos I have enough Sampletekk, not sure most of the NI ones are worth keeping that existed in previous versions of Komplete.