People from highschool add me on instagram and Facebook to just snoop or promote should I delete them?

This is the fourth person who’s added me to either snoop and not chat and I don’t get what the point of the add is…we weren’t really friends in HS. one of the girls who added me I think only did it because she has a brand label of clothing and she is just looking to gain a customer (I’m assuming it’s a tactic )