Unfortunatly parts editor is a work in progress and at present can't make those kind of changes. To do so you would need to save it as a new part (without any changes except maybe to the metadata to explain whats different about your new part) and the edit the svg files with an svg editor such as Inkscape (which I use because it is open source, and is thus what a lot of us use). Old_Grey's videos explain that too, but if you aren't familiar with an svg editor (as I wasn't 
) it has a steep learning curve. I suspect that Sparkfun cloned your jack off the one with bypass switches (which uses the extra pads) and didn't delete them. While you are welcome to try Inkscape, you may find it easier to use this part that I just edited off the one you have, cleaned it up a bit and deleted the two extra pads.
3.5mm Audio Jack_no_extra_pads.fzpz (7.9 KB)
The pad holes here are 0.051181 (which will likely round up to the standard size of .052). Once you are familiar with parts creation and Inkscape this is a pretty short task, its just getting that experience that hurts (although it is worthwhile if you like Fritzing which I do). If you need changes to the power plug I can do that too if you specify a hole size. Note that the fab houses usually have a list of standard drill sizes. My local fab has this set for free (they have other sizes, but they charge if you use them):
.0197
.0280
.0350 ic pins
.0380 .25 connector posts
.0420 1n4001 diode holes
.0520
.0595
.0860
.1250
.1520
I expect the Fritzing fab has a similar list on their web site somewhere.
Peter