Descript automatically syncs your Projects to the cloud, so you can remove the files from your computer at any point to free up disk space.
To remove downloaded files associated with a Project, open a new Drive View window (File > Open Drive View) click on the Project's ellipsis (...) menu and select Remove Download.
The next time you open the Project, Descript will re-download the files.
Remove Download vs. Delete
Please note that removing a download is not the same as deleting your project. Removing the download only removes the local media files from your computer to save space, whereas deleting a project will delete the project permanently from your account and it cannot be recovered.