Attaching/Detaching the Joy-Con Controllers From the Joy-Con Grip
You can attach the left and right Joy-Con controllers to the Joy-Con grip to use them as a single controller.
How to attach
Remove the Joy-Con controllers from the console and slide them down the rails on either side of the Joy-Con grip.
How to detach
Hold down the release buttons on the backs of the Joy-Con controllers and pull them up.