How can i get my mac hard drive back to one partition?

i have an older kind of mac and a few years ago i split the hard drive into 2 partitions to get bootcamp on my mac...i obviously did something wrong because there is only 5.68 GB on that partition and it just kinda sits there...is there any way i can put that hard drive back into one...i tried disk utility to put it into one portion (when i was clearing my mac of all the old stuff) but that didn't work...if i cant put it into 1 portion then what is a good use for it?