Yepper. That is indeed how you should do it.
It does not benefit you in anyway, to let entities walk all over you and sets a bad precedent for the future.
They will respect you more, if you respect yourself enough to stand up for what you truly believe in. I’m not saying be disrespectful, but lay it out like it is- clearly.
Some spirits will walk all over you, just like some people will, if you let them.