If you make a mistake, no one will lose the power of speech. Dig up the whole plant on a cloudy day so the plant won't dry out too quickly. Pull the plant in half, or, if it's really big, use a pruning saw. You can cut the plant into more pieces, but be sure each leafy part has some roots attached. You have to be wealthy to have a beautiful garden.
Some rich people do have beautiful gardens, but packets of seed still cost only a couple of dollars.
And all you need to grow almost anything well is good soil full of compost. Bagged compost is available at any garden center, but I make my own. Every time the pile gets to be about 2 feet tall, I throw a couple of inches of earth over it. You can grow almost anything if you mix plenty of compost into the soil. That's all there is to it.