IPhone – Symlinked MobileSync folder but still “not enough free space”

It depends whether the remaining files you have are from an encrypted backup.

It won't be feasible to read your backup data if you have an encrypted backup with no Info.plist, Status.plist, or Manifest.mbdx files

However, if your backup wasn't encrypted, it will be possible to read that data. You'll find that whilst the filenames are unhelpful (they're SHA-1 hashes of the file's internal path), the file contents easily readable. It's only the filenames that'll be lost.

If you're looking for images, try renaming a bunch of the files to have .JPG extensions, and see whether Windows Explorer or macOS Finder previews them for you.

There are a few approaches for digging into what's there in bulk. You mentioned using iPhone Backup Extractor, and there's a guide on how a use "Bulk Rename Utility" to read backup data when in this situation.

Yes, it is safe to delete it, if you are sure you want to lose those backups.

To do so, in a more elegant way, just:

1. Open iTunes Preferences
2. Click Devices
3. Locate the backup for the iOS device you want to delete, select it, and click Delete Backup.
4. Confirm you wish to remove the selected backup by clicking Delete Backup.
5. Click OK to close the iTunes Preferences Window.

Extracted from Apple's support document about iOs backups.

Confirmed: Deleting through iTunes will delete all the backUp files of the selected device.