Yes, that is possible to do, though you won't be able to rectify the space lost on your remaining partition without formatting your hard drive, unless you use a program called Partition Magic which can then after deleting the partition, make the remaining one fill the whole drive up again, though its not free by all means. Though I've heard its rather simple to use and get working.
EDIT: I edited this post because I read your post wrong, and so you can use partition magic to rectify the space lost, and for the deleting of the partition (it wouldn't be fair of me to have edited to add the part about the disk manager now), so just follow the post by Knight to do that
Though after doing that, do note that you will have half a drive, as without formatting, you won't be able to get the space you've lost back I don't think within windows, though you can wipe that partition.
Some information from Kage to Rage