Clean up disk space for Void Linux

With continuous upgrade, the disk space become less on Void Linux:

# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        470M     0  470M   0% /dev
tmpfs           495M     0  495M   0% /dev/shm
tmpfs           495M  464K  494M   1% /run
/dev/sda1       7.9G  6.0G  1.5G  81% /
cgroup          495M     0  495M   0% /sys/fs/cgroup
tmpfs           495M  125M  370M  26% /tmp

Only 1.5G left. After referring this document, I do following cleaning-up:

// Cleaning package cache
# xbps-remove -yO

// Removing orphaned packages
# xbps-remove -yo

// Purging old kernels...
# vkpurge rm all

Now the free space is doubled:

# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        470M     0  470M   0% /dev
tmpfs           495M     0  495M   0% /dev/shm
tmpfs           495M  460K  494M   1% /run
/dev/sda1       7.9G  4.3G  3.2G  58% /
cgroup          495M     0  495M   0% /sys/fs/cgroup
tmpfs           495M     0  495M   0% /tmp