I spent quite some time to figure this out so I thought I’ll share it for the next person who want to do this: suspend a user via the API.
If you use Discourse web interface, you can go to the route
/admin/users/:username and then use the
suspend button. You can find the
suspend method in
UsersController. Well turns out that you should not use
:username in the route but the
To conclude, to disable a user via the API, use