I think I should take down someone else's lost cat flyers
Why would bother to remove a lost cat flyer?
I think it's wrong to spend money on cats instead of people.
It would be very rude to remove someone else's sign. It's fine for you to not spend your money on pets, but other people can spend their money however they want.
I hate people who spend their money on animals. I'm willing to remove the signs to prevent more money being spent on a cat.
What you're planning to do is wrong. It's none of your business what the cat's owner does with their money. By taking the sign down you may prevent them from finding a pet that they obviously love.