I know this question will probably come up multiple times, so I decided to fill in on some material for people who like reading and want thorough solutions.
First and foremost it is always good to educate yourself. Read about Android viruses (https

/www.lookout.com/know-your-mobile/android-virus).
Afterward, you can try a more thorough approach and explanation on removal(http

/www.2-spyware.com/remove-android-virus.html).
Lastly, don't forget to educate yourself about potential threats and malicious applications. Read about them before downloading, if you suspect something even slightly off, investigate. More about one of the threats here (http

/thehackernews.com/2017/06/android-google-play-app-malware.html)