how do i uninstall sage?

edit

From the Terminal, you can also do

mv 'sage directory here' ~/.Trash 
mv ~/.sage ~/.Trash

to move the two directories to the trash, and then you can empty the trash at your convenience. (If you don't care about removing the "~/.sage" directory, then you can just drag your Sage directory to the trash in the Finder.)

Exit sage.
Open the Terminal Application (command-line), it's under /Applications or /Applications/Utilities

rm -rf "sage directory here" (Be careful!)

If you want to delete your user files also (notebooks, etc),
rm -rf "~/.sage/" (Again be careful, or you'll delete things you don't want to.)