0 bytes disk space Fedora 23

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new to learning Linux i have fedora running in a vitualbox on windows 10

hello new to learning Linux,i have fedora running in a vitualbox on windows 10,ran into problem "Low Disk Space on "Filesystem root" the volume filesystem root has 0 bytes disk space" forced to logout, i can't do anything,i have uploaded video screenhot of the problem link text how can i free up space, without having to uninstall things? what is chewing up all my diskspace?

0 bytes disk space Fedora 23

any help would be great...cheers

[lharvey@fedora23 ~]$ df -h
Filesystem                        Size  Used Avail Use% Mounted on
devtmpfs                          365M     0  365M   0% /dev
tmpfs                             375M  260K  374M   1% /dev/shm
tmpfs                             375M   11M  364M   3% /run
tmpfs                             375M     0  375M   0% /sys/fs/cgroup
/dev/mapper/fedora_fedora23-root  6.5G  6.5G     0 100% /
tmpfs                             375M   32K  375M   1% /tmp
/dev/sda1                         477M  100M  348M  23% /boot
tmpfs                              75M   12K   75M   1% /run/user/42
tmpfs                              75M   12K   75M   1% /run/user/1000
[lharvey@fedora23 ~]$