By default, all lights are automatically added to each render layer. To override this behavior, open the Render Setup editor and disable Options > Include all lights in each render layer by default.
You can do the following to add specific lights to a render layer:
Disable Options > Include all lights in each render layer by default.
Create a lights collection in your render layer by dragging and dropping it the from Scene settings to the render layer.
Select the Lights collection. In the Property Editor, add lights to this collection by entering an expression, or by selecting the lights and clicking Add, or by doing both. See Create a collection for your render layer.
You can only add lights to a Lights collection.
For convenience, the Include all lights in each render layer by default option is also available in the Lights collection Property Editor. If you change your mind and decide to include all lights in your layers instead of only specific ones, re-enable this option. This is a global setting, however, and enabling this option affects all layers in the scene.
Click View All to verify the contents of your Lights collection.
Create an override on a light, and it is automatically added to your layer.
For more information regarding light overrides, see Create light overrides in your render layer.
Override the Enable attribute of a light to disable it in your render layer. See Create light overrides in your render layer.
The Include all lights in each render layer by default setting determines whether lights are automatically added to each render layer. This option is enabled by default, and can be disabled via the Options menu or in the Lights collection of each render layer. When this option is disabled, only lights that are explicitly included via the methods outlined above are included in each layer. You can disable this option at any time, in a new scene or in any legacy scene.
This setting is saved with your preferences in the option variable renderSetup_includeAllLights, and persists upon restarting Maya.
You can also control this option by setting the environment variable MAYA_RENDER_SETUP_INCLUDE_ALL_LIGHTS. A value of 0 disables the option, and a value of 1 enables it. The environment variable takes precedence over the preference. Once the environment variable is set, the menu option is greyed out and follows the value of the environment variable.