Lucky Wheel is a fun new way to earn more Rocks, which allow you to download more manga, purchase iMessage stickers and manga artworks in Manga Rock app.
You can choose to get notified when the new spin is available and can easily turn it off by following this instruction:
Step 1: Open Manga Rock then go to Account tab
Step 2: Tap on Advanced Settings
Step 3: Turn on / off notification for Spin Available