To resize swap partition:

sudo nano /etc/dphys-swapfile
sudo dphys-swapfile setup
sudo dphys-swapfile swapon

To check the current swap status:
swapon -s

To turn off all swap:
sudo swapoff -a

To turn on swap as defined in /etc/fstab:
sudo swapon -a

To turn on swap, using a specified file:
sudo swapon /var/swap