rear brake light adjustment

Hi everyone,
I hope for some help.
I noticed that my brake lever was rubbing the crankcase and so I pulled it out
and rotated a little.
Since then my rear stop light is always on,
I know that it is possible to adjust,
but I don't understand where and how,
I took a look at the service manual,
but i didn't solve it.
Anyone have any idea?
Thank you