Since Linux uses a format unknown to Disk Utility you will need to remove the partition using Linux. Boot from the Linux Live CD. Use the Try it out option and use the Linux Disk Utility to delete the Linux partitions - includes the Swap partition. Then when you reboot OS X Disk Utility will see just an unused space that can be occupied by the immediately above partition or you can add a new partition in that space. However, unless you restore the drive to on single volume Boot Camp cannot work with it. Boot Camp also will not work if you have foreign boot loaders still installed, like GRUB.