To find out where disk space is being used:
Get to the root of your machine by running
# cd /
# sudo du -h --max-depth=1
Note which directories are using a lot of disk space.
cd into one of the big directories.
# ls -l
to see which files are using a lot of space. Delete any you don’t need.
Repeat steps to run once you cd into the directory with the largest size
sudo du -h --max-depth=1