If by "local storage" you mean the copy of cloud originals stored in accordance with the preferences>Local Storage tab, be aware that they are copies of the cloud originals which are managed exclusively by the local Lightroom desktop app. Delete an image from the cloud, and the local copy is also deleted.
If you have changed plans, one assumes that you now are using Lightroom Classic. In which case, the simplest means of retaining the cloud images would be to enable sync in the LrC catalog. That will result in all the images in the cloud being downloaded into the LrC catalog (full copies of the original files), and once in the LrC catalog they are no longer managed by Lightroom.....which means you can the safely delete the images from the cloud, and the LrC copies are untouched.
Before enabling sync in the LrC catalog, however, visit the LrC Preferences>Lightroom Sync tab and set the download location for the synced images to one of your preference (the default would be an obscure folder in the user Appdata>Local library). Also, you have the option to have the downloaded images automatically stored in a date-based folder scheme (based on the image capture times).