Expand swap partition-Ubuntu manual Configuration

Because of the automatic partition used during installation, my swap partition is more than 800 mb. Recently I plan to use the sleep function. I found that the swap partition is always unsuccessful. It is reported that the swap partition is not large enough, originally, UBUNTU used swap partitions to suspend the system, and my machine had 2 GB of memory. Therefore, to use the suspension function, we need to expand the swap partition.

I have a post discussing many things. The steps are simple: [discussing] How to expand swap partitions?

The procedure is as follows:

Dd If =/dev/Zero of =/swapfile COUNT = 2048 BS = 1024 K
Mkswap/swapfile
Swapon/swapfile

The first step is to divide a swap space, the second step is to make the file system into a swap partition, and the third step is to enable the swap partition.

The problem I don't understand now is whether the original swap partition is useless. How can I release it?