one can do it your self, and I do it for my self, but I have two debeaders, and some times need both of the, a number of good tire irons, an air powered fluid pump, 20 ton jack, vice grips, and so on, and the experience to do the job,
I have had a number of "new" tubes split on a seam, if you do plan on doing this just buy a new tube,
on the rim wash it up very good, and a few rolls of duct tape put on the rim can protect the tube from a rusted up rim, a good cup brush on a 4" grinder helps a lot, (if doing it your self repaint it), lot of drying time is needed,
one can get a lot of the fluid out if the tube is not tore loose from the valve stem, by airing up the tire and then rotate the stem down to the bottom of the wheel and with a hose put in to a plastic drum, or two, depending on the size of the tire, one may have to do this a number of times, but one can get about 90% out this way (I would guess by letting the jack down and flatting the tire at the last would get a lot of the last (below the vale stem with it down), to where one could work it out the tube out of the tire and rim with the tire off the wheel one sided, Gemplers has some tips on tire repair,
near the top of the page there is a menu with various aspects of tractor or large tire repair,
Changing a Tractor Tire - Dismounting | GEMPLER'S mounting, dismounting, liquid ballast. and some on safety,
use a special tire gauge that is made for liquid ballast filled tires, the crap will destroy a gauge or even a air head at times if it get in to them
(can you air up the tire and drive the tractor to a location where they can work on it)
I would suggest for a beginner, hire it done, and watch and ask a lot of questions, before trying it your self with out experience.