Bienvenue !! The images didn't quite work out but they should help convey the process. Ocasionally you will see bedframes that you can acquire. They can be used to make durable garden stakes. Tall enough to hold a pea or cuke fence. Deconstruction is a fairly simple process but it takes some work. You have two indentical halves. First use a hammer to knock the wheels off. Don't smash them, pop them out. Use a hacksaw to cut the rivets connecting the long piece from the two short pieces. Then just yank the short piece off the long piece. Sometimes they are stubborn and need to be drilled out. You are done with the long pieces unless the have brackets on both ends. If they do you should remove the bracket from one end or you will not be able to drive the stake into the ground. There is some variation in the way the short pieces are designed to connect. Some bolt, some have sliding connectors. In that case just drill off one connector and bolt the two pieces together.
You will need a hacksaw, a hammer, a punch and a drill. A grinder would also work. It's all about getting the rivets out of the way. Whatever works.