"I do not like working in a shop!"
Translation:Dw i ddim yn hoffi gweithio mewn siop!
No, afraid not. You'll always need the yn (or 'n) before most verbs, including "hoffi". And whenever you use a verb after "hoffi" to say that you like doing something, you never put an 'yn' in there. Just the way it is! (Let me know if you want a more in-depth answer :))