removing the capital one shopping extension

I may have screwed up by falling for this extension, but there was a capital one shopping extension that needed to be loaded into safari for price comparisons. I think it did have to download from the app store. Maybe it was for the better, but for some reason the website wouldn't take the password safari tried to generate. I went into preferences and tried to remove the extension and I kept getting an error that it was in use and sent me to the finder window. I still couldn't remove the extension from finder because I was told it was in use. I shut down safari and was then almost able to drag it to the trash. One thing that bothers me is that in order to drag it to the trash, I can to give my admin password.

Is this a malware app? Is there any way for the app to see my admin pw when I had to enter it to delete it? I just want to make sure and make sure this app isn't watching me in the background if I have to change my admin pw per any of your recommendations.

Thanks.