We have a server that currently has one disk visible under System Manager. That disk has been divided into two primary partitions (C:,D:). The C: drive is running very low on space and so we need to somehow remove the D: drive partition in order to extend the C: drive. When I right click the D: drive, there is no option to delete the partition. We have ensured that there is no files on the D: drive. As well, whenever we try to format it, we get an error that says "Windows cannot format this drive. Quit any disk utilities or other programs that are using this drive, and make sure that no window is displaying the contents of this drive. Then try formatting again.". We don't have anything open that would show the contents of the D: drive. I have attached an image of our current setup on that disk from Disk Management.
Any suggestions on how to delete that partition? It has over 400GB, which we'd love to assign to the C: drive.