Managing files on your nanoHUB account is important. If you run out of space, you may not be able to run simulations.
The best way to access your files is to use an SFTP client to connect to nanohub.org, port 22, with your nanoHUB username and password. From there, you will be able to browse the files in your home directory.
Filezilla is a popular SFTP client that can be found at https://filezilla-project.org/. SFTP is a standard protocol that is widely used to access files on remote hosts, with tutorials and other resources available on Google as needed.
You will need your nanoHUB username and password to access your home directory on nanoHUB via SFTP. After connecting you can view and remove files as needed. Once you have decreased the amount of disk storage used (<10 GB for standard accounts) you will then be able to launch and use tools.