I was not able to find a way to delete a custom macro that I just created using the latest Textmate version. Surely this should be fairly simple task?
The only option in the Edit Bundle section is the enable/disable the macro.
Select the macro in the bundle, and either use the hotkey (Command + Delete) or the menu;
If for some reason that doesn't work, the macros themselves are stored in
~/Library/Application Support/Avian/Bundles/[BUNDLE NAME].tmBundle/Commands
or
~/Library/Application Support/Textmate/Bundles/[BUNDLE NAME].tmBundle/Commands
And you can just delete the files from there.