Yes. Here's how:
- Select the Color tab in the left panel, to change the existing background color of a Sticker.
- Change the sticker's background color by:
- Selecting one from the color palette
- Selecting via the Eyedropper Color Tool
- Specifying a custom color or adjust the CMYK values
- You can also choose to have a transparent background by choosing the No-Color option, i.e. the white circle with a redline in it.