I installed ruby1.9.1 from source using
sudo make install. How can I uninstall this?
Basically I just don't want 'ruby' to map to ruby1.9.1, but instead the default 1.8.7.
sudo make uninstall does nothing.
Check the makefile for a 'make uninstall' target. Sometimes they come with those.
Failing that, the best you can do is carefully read the 'make install' target and then manually undo what it did.
This is more of a ruby specific thing, so it almost now belongs in SO. Here is what to do (as per this blog post.