I'm trying to get postgis running on my machine. Running brew install postgis seems to have installed postgres 9.2.1 on to my machine. I would like to remove my previous version 9.1.2 to keep my environment clean.

Running brew uninstall postgres removes 9.2.1.

What's the best way to do this?

UPDATE

nai@nyc ~  $ brew versions postgresql
9.2.1    git checkout ed92469 /usr/local/Library/Formula/postgresql.rb
9.2.0    git checkout 2f6cbc6 /usr/local/Library/Formula/postgresql.rb
9.1.5    git checkout 6b8d25f /usr/local/Library/Formula/postgresql.rb
9.1.4    git checkout c40c7bf /usr/local/Library/Formula/postgresql.rb
9.1.3    git checkout 05c7954 /usr/local/Library/Formula/postgresql.rb
9.1.2    git checkout dfcc838 /usr/local/Library/Formula/postgresql.rb
9.1.1    git checkout 4ef8fb0 /usr/local/Library/Formula/postgresql.rb
9.0.4    git checkout 2accac4 /usr/local/Library/Formula/postgresql.rb
9.0.3    git checkout b782d9d /usr/local/Library/Formula/postgresql.rb
9.0.2    git checkout 2c3b88a /usr/local/Library/Formula/postgresql.rb
9.0.1    git checkout b7fab6c /usr/local/Library/Formula/postgresql.rb
9.0.0    git checkout 1168d8f /usr/local/Library/Formula/postgresql.rb
8.4.4    git checkout c32bea0 /usr/local/Library/Formula/postgresql.rb
8.4.3    git checkout 237d1c5 /usr/local/Library/Formula/postgresql.rb