Like Hissin said, there should be no reason to mess with that on a radiator install...
Drain the radiator, remove the hoses, remove the tranny cooling lines (automatic only), unbolt the fan from the water pump pulley and slide it forward into the shroud, unbolt the upper mounting brackets and pull up.
Your picture is the high pressure refrigerant line coupling.
As mentioned, do not disconnect them unless you have discharged all of the refrigerant from the A/C system. Keep in mind that to fulfill the requirements of the EPA, you are required by law to recover any refrigerant that still remains in the system. How (or wither or not) you accomplish this is up to you.
If you absolutely must disconnect them and have no refrigerant left in the A/C, here are the tools.
Look in the A/C repair section for the tools. They look like little plastic top hats. You will need the 1/2" & 5/8" ones. The hat shaped section goes on facing the large part of the coupling. Then you press hard on the brim until it forces the sleeve into the coupling and releases the spring. You may need someone to pull on the line while you press on the coupling. Put some PAG refrigerant oil on them when you put the line back together.
When you reconnect the lines, you will need to replace the Accumulator/ dryer assembly because it will suck up moisture from the air. Moisture and hot refrigerant make acid that eats up the A/C system from the inside. Nasty stuff. You must have the system vacuumed down to remove the air and moisture prior to rechargiing it. Click on the link in my sig for R134 conversion help.
Indeed you do not need to remove that to remove the stock radiator.
If you do indeed want to remove it anyway for whatever reason you can buy the quick disconnect tools for between 5 to 15 dollars at any autopart store (i got my set at napa for 8 bucks).
Usually that connection is for lines that contain a fluid under pressure -- such as a/c lines, power steering lines, fuel lines, etc.
You just have to drain the radiator at the petcock, disconnect the two hoses, and if you have tranny lines going into the radiator, disconnect those as well.
Then undo the bolts holding the overflow resevoir,the fan shroud and the two upper hold downs, and boom it comes out.
Simple as that.
Be sure that if you get a replacement that is aftermarket, that you get one for the vehicle. Some more expensive replacements like Be-Cool radiators do not have any of the sheet metal/aluminum at the top to mount the radiator like the stockers have.
So you have to end up fabbing something up.
Not too hard, but again, a pain in the arse if you buy something and then realize its not just a straight up drop in replacement.
I have a be-cool, and although it was expensive, my car never overheats, I beat the ever loving crap out of it, have a turbo 408 stroker in the notch that the radiator is in, and a 180 t-stat. Daily driving in bumper to bumper traffic on a hot, humid day like today was, is no problem.
Just my experience, sorry for the long winded post.