photo libraries after upgrading to iCloud Photo Library

We held on to using iPhoto for as long as possible, but for the last few months have made the slow migration to Photos, merged multiple libraries removing duplicates and signed up for iCloud Photo Library. Every device my husband and I have is set up to see the complete library in iCloud Photo Library. At this point, do we need to keep the large library files that are on our laptops? If the pictures are truly synced and stored in the cloud, I don't see the need to keep the original libraries that were stored locally for over a decade. Or is there some coding that would need those files kept on our laptops?

Thanks!