User-agent: Googlebot
Disallow:

User-agent: AdsBot-Google
Disallow:

User-agent: AdsBot-Google-Mobile
Disallow:

User-agent: Mediapartners-Google
Disallow:

User-agent: Bingbot
Disallow:

User-agent: AdIdxBot
Disallow:

User-agent: Slurp
Disallow:

User-agent: IonCrawl
Disallow:

User-agent: SemrushBot
Disallow: /

User-agent: AhrefsBot 
​Disallow: /

User-agent: MJ12bot
Disallow: /

User-agent: PetalBot
Disallow: /

User-agent: *
Disallow: /