According to this documentation:
Cloud Shell provisions 5 GB of free persistent disk storage mounted as your $HOME directory on the virtual machine instance. This storage is on a per-user basis and is available across projects. All files you store in your home directory, including installed software, scripts, and user configuration files like .bashrc and .vimrc, persist between sessions and count towards the 5 GB limit.
I understand that I ran out of disk space but the docs didn't mention how to free up space in home directory. Is there any cloud shell command to run for me to free up some space? Still a novice in GCP.