How do ask you not speak French in French?

You can ask someone not to speak French in French by saying:

"Parlez-vous anglais?" (Do you speak English?)

This is the most direct and polite way to ask someone to switch languages.

You can also use a phrase like:

"Je ne comprends pas le français." (I don't understand French.)

This will let the person know that you are struggling to follow the conversation and that you would prefer to speak in another language.

Finally, you can simply say:

"Excusez-moi, pouvez-vous parler plus lentement?" (Excuse me, can you speak more slowly?)

This might encourage the person to simplify their speech or even switch to another language if they think you don't understand.

Remember, it's important to be polite and respectful when asking someone to change languages.