Hello,
I updated my wife's laptop by swapping out her 1 TB HardDrive to a 1 TB SSD Drive. It's so much faster on boot, quieter and battery seems to last longer.
Well, I didn't want to waste the old 1TB HD. So, I put it into a USB 3.0 external enclosure.
I formatted it but the couldn't get to the Recovery/System EFI partitions to delete. [Don't need them anymore since they are on the SSD in wife's laptop.]
I tried in my host Desktop running Windows 10. I ran diskmgmt.msc, but when Right-Clicking on those partitions, the options are not available to delete. If I Right-Click on the 'Basic Data Partition', those options are available.
Then I tried FDisk, but it's not in my Windows 10 OS. I used it a lot in Windows 7.

Bear in mind, this is re-purposed as an External 1 TB HardDrive. I no longer need it for the original Laptop. The Recovery tools are installed on the SSD that replaced this HardDrive.
Any ideas?
I can live with 100 plus GB unavailable, but it just bugs me I can't blow it away.
Thanks in advance for your help!
Danielo