Macs use a type of filesystem called HFS (HFS+ for OS X). Windows can't read HFS. To access the information, you'll need to install a program which can read HFS partitions. (Please note that not all of these can write to HFS partitions. See the last paragraph is you regularly need to write to HFS from Windows.)
https://www.makeuseof.com/tag/4-ways-read-mac-formatted-drive-windows/
Clearing the partitions is simple. Just right-click them and delete. Once the entire SSD shows up as unallocated space, you can create new partitions on it.
On rare occasions Disk Manager will have problems deleting unrecognized partition types like HFS. In that case, you may have to use a partition manager program like Minitools Partition Wizard to delete it.
https://www.partitionwizard.com/free-partition-manager.html
When you create new partitions on the drive, if you plan to share it between Windows and Mac, the filesystem you want is exFAT. It was specifically designed to be readable and writeable on both Windows and Mac to facilitate file sharing. Performance is a bit worse than HFS+ or NTFS though, so I would use it only on drives which will regularly connected to both types of systems. If the drive will spend most of its time connected to a Windows box, I'd format it as NTFS, then buy a USB stick formatted as exFAT to transfer data between the two.
Facebook
Twitter
Instagram