I'm Miles from the Social Care team at Shopify. I've had a look at your website on my phone and I can see a green pop-up as shown below:
This pop-up is also shown when I visit your site on a desktop. The pop states "Powered by Poptin". Is that the correct pop-up? I don't see any reference to POWr at all on mobile or desktop.
If it is still appearing for you it may the result of leftover or residual coding. If this is the case, you'll need to reach out to POWr directly to assist you in removing any of the leftover code.
I would also suggest clearing the cache on your mobile browser to see if that resolves the issue since I'm not seeing the incorrect pop-up on my end.