Uninstalling.

Quit Current and drag it to the Trash. Your downloaded files are wherever you saved them and are not touched — deleting the app never deletes what it downloaded.

Three things stay behind, holding your library, your settings and the list of peers Current has learned. Delete them and Current starts over as if newly installed:

• ~/Library/Application Support/Current
• ~/Library/Preferences/org.current.torrent.plist
• ~/Library/Caches/org.current.torrent

If Current was opening your magnet links, macOS hands them back to your previous app once Current is gone. You can also set that yourself in System Settings, under Default Applications.