SUBREDDIT: r/relationships
TITLE: Me [25 M] with [19 F] hook-up. Said I would call but don't want to. What is the right thing to do?
POST: Basically had a fun drunken night which led to making-out and her sleeping over with girl I met that night, no sex but "stuff". I got her number and told her "I have your number" suggestively in the morning. She's too young and other in a different stage of life. Have had very few hook-ups. 

No real interest in seeing her again but feel stupid for saying I would. Should I call/txt saying it was nice but no thank-you? Or just not do nothing?

I know I shouldn't have lied and I feel pretty stupid about it. I know this isn't really a "relationship question". Not a random hook-up guy. And it was definitely a moment of weakness/stupidity in my currently unconfident self to try and be a player. Only ever really tried for girls I am serious on.
TL;DR: 
Hook-up with much younger girl. Said I'd follow-up but don't want to. No interest in anything more. What's the right thing to do?