Need help moving my brother to a mental institution?

These types of situations can be tough. Especially because you don't want him to think you're just trying to kick him out. You want him to get proper treatment and he can no do so living ordinary life. Your best option would sit and talk with him. See how he feels about getting treatment for a few weeks, nothing too serious. If he allows you to admit him or he admits himself, the institution will have to sign his discharge papers upon how well he can handle things on the outside. Best of luck to you my friend! Stay strong for both of you and stay by his side! You may be all he has left.