You can enable and disable a routine in Parent Mode on the Routines screen (second icon from the left). When a routine is disabled, it will not appear in Kid Mode or on the Brili for Pebble app.
Simply drag the routine you want to disable to the left, and this will expose the Disable button as shown below:
To re-enable a routine when it is greyed out / disabled, you can tap on the green Enable button in the lower right.
Note: if you recently downgraded from Brili Unlimited or Brili Extra, you may need to re-subscribe in order to activate routines that exceed your plan's routine limit.