Replacing a flanged copper pipe?
That copper tubing has been brazed with silfos or a similar type of solder. separating that joint will take a lot of heat. The standard soldering torch will not get hot enough to melt this product. You will need a "turbo torch" or an oxyacetylene torch to unsolder this fitting. If you are not versed in this type of equipment you better call a plumber. However if the copper is only kinked on the side shown you may not need to replace the kinked piece unless it is leaking. It probably is not restricted enough to reduce the water flow by very much.