When you swipe right on an app, you'll see quick actions (called shortcuts) if the app provides some. Shortcuts are managed by the app that provides them and can change dynamically.
Remove All Shortcuts of One App
[Requires Niagara Launcher v1.4 released in October]
Long-press on the app pop-up from where you want to remove the shortcuts. Then, tap on "Edit shortcuts" and deselect the shortcuts from the list.
Remove just one or few shortcuts
It's not intended to filter out some of them. Nevertheless, you can do that with the help of Niagara Pro and Sesame. Here's how: In Niagara Launcher, swipe right on the Contacts app and tap on the edit pen at the top right. Then, tap on "Edit shortcuts," and Sesame will open. From here, you can toggle off shortcuts you don't want to be listed anymore.