Toshiba External Hard Drive triggers NTI EZ on intial boot.

PolarNettles said:

Yes, that likely has the UEFI code for the NTI backup software. If you're sure you don't need it you can delete the partition. I believe you should be able to restore it later with the tool at NTI - Backup Software, Migration Software, Cloning Software, Sync Software, CD DVD Burning Software - Official Site .

Unable to delete the partition; all options in disk management for the partition are greyed out, apart from "Help".

You can use EaseUS Partition Master Free - Free Partition Magic alternative and Partition Manager Freeware for Windows XP/Vista/7/8/10. or follow options 2 or 3 from Delete Volume or Partition in Windows 10 Hardware Drivers Tutorials .

Matthewzelah said:

Unable to delete the partition; all options in disk management for the partition are greyed out, apart from "Help".

Yes, Disk Management protects what it regards as system partitions. You can delete it from a Command Prompt (Admin) with DISKPART. Option Two in this tutorial.

https://www.tenforums.com/tutorials/96684-delete-volume-partition-windows-10-a.html#option2