Uninstall

Use the app’s own Uninstall option instead of dragging the app to the Trash. It removes everything Puffin put on your Mac, in this order:

1. Turns capture off.
2. Removes the proxy configuration.
3. Deactivates the system extension. macOS may ask you to restart before it finishes.
4. Untrusts and deletes the certificate authority.
5. Optionally deletes Puffin’s data folder, ~/Library/Application Support/Puffin Proxy, and the app’s saved settings.

If one step fails, the later steps still run. Puffin never deletes anything outside its own folder.

Afterwards

You can check the result yourself:

• System Settings ▸ General ▸ Login Items & Extensions should not list Puffin.
• Keychain Access should have no Puffin certificate or key.

Only remove the certificate

To keep the app but remove the certificate, use Remove & Untrust in Settings ▸ TLS. Puffin then cannot decrypt HTTPS until you create and trust a new one.

Stop capture without uninstalling

Turn capture off from the menu bar. You can also remove the proxy configuration in System Settings. In either case your traffic goes back to normal.