Old window caulking can be an eye sore and if it is dried out and cracking, it is no longer serving it's purpose. Drafts and other outside elements can enter into your home through open crevices in your window's caulking. In order to combat this problem, it is suggested that you remove the old caulking and replace it with new. The removal of window caulking can be tricky, but not impossible. The use of chemicals is not necessary, but good old elbow grease is.
Begin the process by trying to remove as much of the caulk as possible with a heavy duty putty knife. This is the easiest and most reliable way to remove any loose or crumbling pieces.
Follow up the removal, by using a wire brush to remove any loose particles of caulk that may be left behind.
Apply heat to the caulk by using a heat gun. For the removal of stubborn caulk that just won't budge, the heat gun can be a valuable tool. It will soften the caulk, allowing you to remove it easier with your putty knife. Just don't overheat it! You want to soften it, not melt it into a bigger mess.
Continue to work at removing the caulk from the window until the majority is gone. This will take some elbow grease, but it is better than exposing yourself to a heavy chemical process that has no guarantee of working.
Using your utility knife, gently remove the caulking from any crevices that your heavy duty putty knife may have missed. You are finished when all signs of pre-existing caulk are removed. At this point, you are ready to apply the new caulking to the window.