Restore Hard Drive?

How do I combine 4 partitions back into my original partition by using the Disk Utility tool?

You'll need to use "erase" and reformat the drive. Make sure the Drive is selected and not just a Volume.
If you have any problems removing the partitions, select the "zero" the disk option.

I want to keep my main partition and erase the other partitions. I click on the individual partitions. I then click on erase. I use the zeros. It then 'mounts' the drive but does nothing more.

Actually you need to delete the unused partitions, then resize the partition you are keeping.

Thats what I thought I needed to do but I cannot delete the partition. How do I do it?

Just to be clear, if I click on the disk drive -> partitions -> select partition -> Press delete -> OK.

It says 'preparing to remove' but it doesn't actually remove anything. i can't help but feel that I would have more luck if I removed these during the start up before the MacOS is started. Is there anyway to do this?

Which version of OS X do you have anyways?