Please see the following post to find out everything about the peek card in Bubble Clouds: Notification Peek card

This is how to remove the peek card:

1. Swipe up on the active watch face to show the peek card
2. Long press on it for the edit screen
3. BTW You can change the background color using the palette icon (make sure to disable the option “Color match card to icon”
   

4. If you want to remove the peek card, use the last option:

   

Alternative way to remove (if you cannot bring it back to the screen by swiping up):

1. Open settings → Add complication

   

2. Select the “Long text Peek card”
   

    

3. If there is a peek card currently, you will get the options “Keep / Modify / Remove“. Select “Remove card”