Find the culprit and remove it

Automagically

Install an AV scanner, scan, and remove.

Manually

Find the culprit

  • If the symptoms appeared immediately after installing an app, that app may be the guilty party

  • If you get ads in the notification bar, then long tap those and then touch on All Categories to learn which app is displaying the ads

  • Go to Settings -> Battery and monitor usage. If you recently charged, Battery usage data is not available. Wait a few hours for the data to become available.

  • Go to Settings -> Network & Internet -> Data usage -> Mobile data usage / Wi-Fi data usage

Found? Then remove.

Remove the malware

  • Go to Settings and tap on Apps & Notifications

  • Locate the app

  • Tap on it, and choose Uninstall

If you see the “Uninstall” option is greyed out or not there at all, then it means that the app has gained privileges.

Remove admin rights

  • Go to Settings -> Security & location -> Device admin apps

  • Tap on the checkbox and then tap on “Deactivate this device admin app”

  • Go back to the Apps & notifications to remove it

Fail

  • If removing admin rights did not work, do a Factory reset

  • If a factory reset did not work, it is probably a very persistent malware (like xHelper) You may wish to analyse it and/or get help.