Well if it is a scam then why shouldn't you delete it? In any case you are both helping user not to fall in a scam and your ad network to remain clean. But just make sure it's a real scam, don't wanna kick someone legit.

(at the same time I realize that in an anonymous ad network users should be smart enough to check always for scams regardless of what the ad network owner does about them, so in theory it would be better if we could let the network run itself but since you are just starting, maybe you should take care of scams yourself)