If you want to remove the swap file you have created and start over. You can use dd to create it. Same procedures but just using dd instead of fallocate.
sudo dd if=/dev/zero of=/swapfile count=4096 bs=1MiB
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
You still have to edit the fstab also.
Edit: I’m not sure when using dd if you have to do this other stuff?
#20 In the link