There is no way at this time that you can become a moderator in the public rooms.  

The same goes for becoming an admin.  The only admins we have are owners of the site.  That will never change.

 Please do not ask if you can be an admin or a moderator; the answer is always no.  

 If someone is bothering you please put them on ignore, this usually fixes the problem. If that doesn't work you can report them from the moderation tab on the person's profile.