16m How to implicitly reject someone before they ask you out?

I posted to this subreddit yesterday asking how to discern the meaning of compliments and many people said that it was likely that some of my friends harboured romantic feelings for me despite me having made it clear to them I wasn’t ready for any of that. This was incredibly alarming as I’m at a place in my life rn where dating is not something I’m interested in as I was badly hurt coming out of my last relationship and as such do not feel like I could be a good partner as I still like my ex (I know that this is just teenage romance and I should get over it etc but the fact remains I would feel guilty dating someone when I liked somebody else). I am terrified that some great friendships will be ruined out of awkwardness should it get to the stage of me asking them out so I need help figuring out how to tell them I only see them as a friend without making it clear I thought they might like me, any ideas?