I don't want to pay for the food I don't eat
Why don't you want to pay?
It's a waste of money and it goes against my principles to pay for goods or services I didn't use.
It's wrong to waste food. But you should pay for the food you do eat.
I'm going to tell the manager, I don't care if they kick me out.
They'll do more than kick you out -- they'll call the police and have you arrested for defrauding an innkeeper. It's expected that you pay for the portion served. If you can't eat it all, there are doggie bags; deciding what percent of the bill you're going to pay is not an option.