Scan and clean machine

Automagically

Install an AV scanner, scan, and remove.

If the symptoms appeared immediately after installing an app, that app may be the guilty party
Look for unfamiliar apps: Swipe through the screen and look for the apps that you don’t remember installing. To see a list of every app you’ve installed from the App Store, tap the Apps icon at the bottom of the store, tap your profile photo, then tap Purchased. If there’s an app on your phone that isn’t in this list (and doesn’t come from Apple), it is likely malware.
Finding out whether your phone is jailbroken isn’t easy. One possible sign, however, is the presence of an app called Cydia. This is an app only available on jailbroken iOS devices. Open the Search bar in your device and look for “Cydia”
Go to Settings -> Battery and monitor usage. Tap on Show Detailed Usage to view the breakdown of foreground and background usage. If you find an app that you don’t recognise, it is a candidate for removal.
Go to Settings > Mobile Network and scroll down to Mobile Data

Found? Then remove.

Restarting your iPhone can, in some cases, get rid of malware. How to do this depends on your iPhone.
Clear History & Website Data:
- Open Settings on your device and tap Safari.
- Tap Clear History and Website Data.
- Confirm.

Delete an app
- Touch and hold the app until it jiggles.
- Then tap the delete button in the upper-left corner of the app to delete it. If you see a message that says, “Deleting this app will also delete its data,” tap Delete.
If the app has a configuration profile, delete it.
- Go to Settings -> General -> Profiles or Profiles & Device Management, then tap the app’s configuration profile.
- Then tap Delete Profile. If asked, enter your device passcode, then tap Delete.
Restart

If this did not work, do a Reset to factory settings
- Make an iTunes backup or iCloud backup
- Go to Settings -> General -> Reset -> Erase All Contents and Settings
- Enter your passcode to confirm the reset
- Set up device again
- Restore the backup to your device. If for any reason you are not able to restore, it most likely contains malware. Then restore one of the previous backups to your device instead, and delete the infected backup from iTunes or iCloud.
If a factory reset did not work, replace device. Most cases of malware are user-made and involve acts like jailbreaking, and Apple’s warranty doesn’t cover this issue.