EISA partitions are OEM utility or recovery partitions, and I would not recommend deleting them blindly (or at all). I guess if you have a full disk image backup then you can get rid of them to reclaim space, but I advise you to just leave them alone.
If you only want to get rid of them so you can create more partitions, there's no need. While MBR partitioned disks can have up to 4 primary partitions, they can also have an extended partition (so 3 primary and 1 extended is possible) inside which you can create as many logical partitions as required.
Of course, newer GPT disks can have up to 128 "primary" partitions.