Olive cutters are the quickest olive removing tool but they are also the most expensive. They are available in a wide range of sizes, though (unlike the olive puller) they only remove one size of olive respectively.
Olive puller #1
This type of olive puller is reasonably priced and though it is a little more time-consuming to use and may not be practical if you have pipes in very tight spaces, it does have the advantage of being able to cut both 15mm and 22mm olives (the most common sizes).
Olive puller #2
This type of olive puller is for use on 15mm pipes only and works in exactly the same way as its brass cousin (see above). The only functional difference between the two is that this olive puller has a ½ inch square drive head, so that it may be rotated with a drive ratchet. This type of olive puller is especially useful if you have a particularly stubborn olive. Its ability to be used with a drive ratchet will provide you with much greater leverage when rotating.
Drive ratchet
A drive ratchet is essentially a handle that can be attached to a square drive to give the user greater leverage when rotating an object such as a nut, bolt, or, in this case, an olive puller.
Other available tools
Olive puller #3
This type of olive puller is less common but is also effective at removing 15mm olives. This tool also has adaptors that allows it to remove 10mm and 22mm olives as well.
It is particularly useful when working in tight or narrow spaces as it can be held vertically or horizontally depending on your needs. Its long handles provide good leverage.
Junior hacksaw
If you have none of the above tools, then you can always use a junior hacksaw to cut through the olive and remove it from the pipe.
Please note: Unless you are careful, you risk cutting into the copper pipe as well.