Answer by AreToo for How to remove password for Jupyter Notebooks and set token again

When you set a password either through the jupyter lab password command or through the browser interface, Jupyter adds the password in encrypted format to a config file which will be located at either ~/.jupyter/jupyter_server_config.json or ~/.jupyter/jupyter_notebook_config.json. This file may have entries titled "ServerApp", "NotebookApp" or "IdentityProvider" with a "password" or "hashed_password" entry underneath. Delete these entries and restart Jupyter Lab to auto-generate a fresh key.