How to remove Get 15% OFF your first order popup?

[werebellstore]

Everytime I open my store, a discount pop up shows up, it says: 

"Get 15% OFF your first order

You'll be notified about the latest sales and discounts"

I can't find out how to remove it, i've deleted all other popups. It's important for me to delete this because the message shows up in english and my store is in a different language.

[asterly]

What is your store url?

[werebellstore]

hi! it's werebell.com

[asterly]

It looks like it's this app that is causing the pop up- https://apps.shopify.com/sendmation

You may need to contact them about code removal if the app is already uninstalled, the app's support team should help you with it.

[Zworthkey · Accepted solution]

@werebellstore 

.sendmation-optin {
    display: none !important;
}

Add this code in 
sendmation-optin.css

thank you.

[werebellstore]

Thank you both!! 

[feel_mc7]

Where can i find ''sendmation-optin.css'' ??