When I woke up this morning, I found my root had filled overnight

du -hx --max-depth=1 /



132M    /boot  

4.0K    /media  

16K /lost+found  

16M /root  

702M    /lib  

4.0K    /OLDHOME  

8.2G    /usr  

73M /etc  

4.0K    /srv  

11M /sbin  

4.0K    /selinux  

8.0K    /.config  

4.0K    /cdrom  

4.6G    /var  

181M    /opt  

4.0K    /mnt  

9.3M    /bin  

4.0K    /lib64  

14G /  

The space is used by /var/cache/polipo (2.7G). How can I clean this up safely?

I tried restarts=>didn't work

Used bleachbit=>the space is not detected in the cleanup preview

PS: I did rm -rf youtube inside /var/cache/polipo and it freed up 2G space. Dunno if it was safe though