Is there no way you could get your hands on another 1 TB HDD just to use it temporarily for maybe 10 - 15 minutes or so and then return it? (I'm assuming you could connect that drive INTERNALLY to your PC in that a vacant SATA data port (connector) on your motherboard is available; if not, then a USB external enclosure to house the 1 TB HDD or one of those SATA-to-USB adapter devices (with a A/C power adapter) would be necessary.)
The procedure would be...
1. Clone the contents of your present D: partition to the temporary 1 TB HDD.
2. After ENSURING that the destination 1 TB HDD correctly contains the cloned contents of the D: partition, delete the D: partition on your boot drive. That will leave unallocated disk-space formerly...