Guys im having trouble with my tablet 10.1

I already factory reset it many times and installed just two of my favorite games

coc and boom beach.. but still the ads keep popping like

the DU speed booster, Guvera music and other stupid games...

im thinking it might have come from google services..

tried installing adaway and antivirus but i need to root my phone which i dunno hw to do..

anyone experience my dilemna? its so annoying...