My neighbor asked me to get her computer running faster a month ago. When I went over there I went to disk clean up on her computer and I was only able to get her freespace percentage to fourteen (it was at five at first).To do a disk defragment fifthteen percent freespace was needed. She went into the other users on the computer (there were three others, for her husband and two kids) and did the disk clean up but the computers freespace percentage didn't go up. Will deleting one of her kids user provide more freespace? Also what else could I do besides deleting unneccesary things on her computer (like old, unplayed games).

right click on c: in windows explorer and hit properties and then click disk cleanup
you will be presented with files that you may choose to delete. these files are user optional, you choose what you would like to delete or keep