Yes. But they have to want to. When you trade, it says "items or pets you want" and "items and pets you will give them in exchange" or something similar to that. You just don't give any items or pets in exchange. Most likely they will say no, but they might say yes!
Je déteste le français. To say "I hate French" (as in the French language) in French, you would say, "Je déteste le français." If you want to say "I hate the French" (as in the French people), you would say instead, "Je déteste les français."