Swap

Swap on NixOS is set with the option: swapDevices. This will be in hardware-configuration-nix. To remove all swap devices from NixOS you must therefore set

swapDevices = lib.mkForce [ ];

This will remove the swap partition/file from being included in /etc/fstab

If you are using GPT partitioning tables systemd-gpt-auto-generator(8) will still mount your swap partition automatically.

You must therefore turn on attribute 63 on your partition in the partition table.

This can be done with gptfdisk or similar:

gdisk /dev/sda
x
a
<partition number>
63
<enter>
w