To add or remove clubs from your bag, first tap on the "Clubs" icon on the bottom of the app screen. Then tap on the Menu icon in the upper right corner of the screen. When the menu pops up, tap on "Manage Clubs".
Tap on the category of clubs you wish to edit (e.g. Woods or Irons). Tap on the club you wish to add or remove (you may tap multiple clubs if you wish to add more than one). To exit this category, tap on the "Back" button in the upper left corner of the screen.
Once you have selected all of the clubs you wish to add, tap on the "Start Pairing (X) Clubs" button. Make sure the Arccos sensors have been installed on the clubs you wish to use, then follow the on-screen prompts to pair each club.