Reappearing apps

I have deleted an app 4 years ago, till date, it's reinstalling , when I delete it, it says " are you sure you want to delete bookmark", I tried everything, closed iCloud app sync, deleted the app, and can't find it anywhere, nor in any search method. But can't get red of it, it also slows my iPhone 6 today, and as soon as I feel the performance of my phone deteriorating, I realize it's back on. I took an appointment in the App Store and couldn't find the reason. It looks like a virus