If you want to take down your gutter, then you need to take out the gutter nails, which are holding it to the roof. You can do this easily, using a ladder, a crowbar, and a hammer.
Step 1 - Remove the First Nail
Start by setting up your ladder at one end of the gutter. Make sure that the ladder is properly secured to the roof. Put on some safety gloves, to ensure that your hands are protected. Take your hammer, and slide the claw piece under the first of the gutter nails. Pull it out as far as you can. Use a pry bar to remove the gutter nail completely. Make sure that you place the gutter nail in a safe waste bin, and don't leave it lying around on the roof.
Step 2 - Removing Other Nails
You can then start removing the other nails. Use one hand to support the gutter while you take out the nails within reach. Move the ladder along the gutter edge as you progress. As the first line of nails is removed, you should hold the gutter to the roof using C-clamps, but the safest way is to enlist the assistance of a friend, or helper. In any event, you must ascertain that the gutter is not going to fall on you or anyone else as you remove its support.