[Rails] error of uninstall gem

gem uninstall rake

Select gem to uninstall:
1. rake-0.8.7
2. rake-0.9.2
3. All versions
> 3
ERROR: While executing gem ... (Gem::FilePermissionError)
You don't have write permissions into the /usr/local/lib/ruby/gems/
1.9.1 directory.

--
You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.