Sorry, not meant in a mean way.

Your D: drive is important. It has all the data to recover (restore) your laptop to factory condition as it was when you first bought it.

If you delete this D: drive partition, and your computer will not start or boot, you will be plumb out of luck unless you are fortunate enough to get recovery cd disks from Toshiba.

If the core problem is a lack of free space in the C: drive partition, you have better options than deleting the D: drive partition.

--Get an external hard drive enclosure, and put a 100-500 GB hard drive in the enclosure. Use that to store all files you do not want to keep on the C: drive. Better yet, use two external enclosures to ensure you have your data backed up twice in case of disaster. That way, if one external hard drive should ever fail, your data is still safe.

If your system is still under warranty, deleting the D: drive could cause it to be voided.

Here's hoping you've not done the removal.