How can I delete stickers on viber?

How can I delete downloaded stickers on viber? I downloaded there a few, and the last one I wanted to download was not possible because there was not enough room in my storage space (still isn't). Now, it says every single time when I open my phone, > there is not enough room in the storage space available to complete this action. Please clear some space and try again. And I am not even downloading anything, it keeps doing it itself. Whatever I do, the window pops up and again, I have to close it. What can I do?