How do you stop having feelings for someone

I have feelings for someone who’s in a relationship and I think he kinda likes me a little too so that doesn’t help at all. But I’m not trying to take him or anything I need to stop liking him like that but I dont know how. Help how do I make these annoying longing feelings GO away. I’ve blocked him. I’m not talking to him outside of work. But we work togather and we can’t change shifts. What do I do!!!!

*wow I’m legit reaching out for help, and no I don’t fucking flirt with him. He flirts with me. He’s nice to me. He’s protective of me at work and i am set the record straight with him that I’m not interested in him. I wasn’t calling anyone stupid but your definitely stupid if you think you can only develop a crush by flirting with them. Your hella rude and you can fuck right off.