I always did it as:

/**/

    Debug code to toggle on and off

/**/

    Other debug code to toggle on and off

/**/

And toggled by removing the last slash on one of the comment lines.

Having two `*` characters worked better for syntax highlighting at the time.

Then I learned about Ctrl/Cmd + / to toggle a line or region on and off.

But I still use the old technique when code editors can't handle where comments are supposed to start and stop and commenting out too much or breaking the indentation, typically breaking around modern CSS's newer features or languages embedded within other languages.