If you are deploying to a server, or you do not want to wait around for rdoc and ri to install for each gem, you can disable them for gem installs and updates. Just add these two lines to your ~/.gemrc or /etc/gemrc:
gem: --no-rdoc --no-ri
Deleting Gemsets
$ rvm gemset use albinochipmunk
$ rvm gemset delete albinochipmunk
$ rvm 1.9.2 do gemset delete albinochipmunk