In addition to removing the Bundles folder, there may also exist a Support and/or a PlugIns folder in any of the three above locations. You also want to remove these, if you want to revert to factory defaults.
After having removed all customized and/or third party bundles, either relaunch TextMate or select *Reload Bundles* from the Bundles → Bundle Editor menu.
Bundles are stored basically in three locations.
1. If you have ever done a `svn` checkout of bundles it would most likely have been done to:
If you encounter outdated bundles (i.e. missing functionality compared to what you read should be there) then generally just remove this folder and instruct TextMate to reload bundles (either by relaunching it or selecting Bundles → Bundle Editor → Reload Bundles.)
2. Third party bundles installed via double-clicking or dragging to TextMate would be installed in:
~/Library/Application Support/TextMate/Pristine Copy/Bundles
You might want to look into the folder before deleting it, to see if it contains bundles which you use. You can always just drag them to your desktop or similar and then re-installing them after wiping the folder.
3. Custom bundles and customizations you have done to either default bundles or third party bundles are kept in:
If you want to revert to the default state of bundles you want to remove this folder. But like with the folder for third party bundles, do check if it contains some customizations you may want to keep.