[Android Central Question]

I'm using an ACE 4 and rooted it with Iroot. But after that i get apps like Prometheus, Tripics, ''service.tools'' ''sysupdate'', flok - Loyalty Cards App and things like that. Also, when i unlock the phone an app store ad appears.
I've already factory reseted and installed a new rom from samsung's page

[Rukbat]

Apps like IRoot are known to slap advertising (and "phone home with your data") apps on the phone while they're rooting.

If you can unlock the bootloader (some Samsung phones, notably bot ones made for the US, can have their bootloaders unlocked), see this page to install TWRP, then try installing Magisk (in TWRP, using its Install function). It's a systemless root, so you can update easily, it doesn't install anything but itself (but there's a whole Magisk-Modules-Repo full of things you can install once you've installed Magisk), and it's developed by a trusdted XDA developer, so you can trust it.

(Don't install SuperSU, which the page tells you to do, just install TWRP.)

Unlocking the bootloader will wipe the phone, but since you installed a new ROM, you probably have backups of anything you need to keep (or you know how to make them). (By the way, if you're reflashing the ROM, you don't have to do a factory reset - the installation will reset ore than a factory reset will.)

If you can't unlock the bootloader, you'll have to use Odin to install SuperSU, so see this page. That also won't install anything but itself. (Trusted developers quickly become untrusted developers if they try tricks like that.)