Root partition is filling up

Root partition is filling up - please check. Current usage: 86%

HA Status          : HA SLAVE (node id: 2)

I've logged into the slave.

df -h

Filesystem Size Used Avail Use% Mounted on
/dev/sda6 5.2G 4.2G 704M 86% /
udev 5.9G 80K 5.9G 1% /dev
tmpfs 5.9G 0 5.9G 0% /dev/shm
/dev/sda1 331M 16M 295M 5% /boot
/dev/sda5 62G 16G 43G 27% /var/storage
/dev/sda7 81G 7.3G 70G 10% /var/log
/dev/sda8 3.5G 472M 2.9G 15% /tmp

du -shx /var/storage/* | sort -rh | head -10

8.6G /var/storage/cores
3.1G /var/storage/swapfile
2.7G /var/storage/pgsql92
697M /var/storage/chroot-http
165M /var/storage/chroot-clientlessvpn
78M /var/storage/chroot-smtp
27M /var/storage/chroot-reverseproxy
17M /var/storage/chroot-pop3
3.9M /var/storage/chroot-ftp
212K /var/storage/samba

What could i delete to get some free space?