How to unask your bridesmaids?

So before covid I asked a my best friends to be bridesmaids and their children to be flower girls etc. They've not bothered asking how things are going, didn't bother giving me their dress sizes or even answer if they wanted makeup booking and gave me loads of reasons why they couldn't come to the hen do. Now it's coming round again I've got serious doubts on who I want to be my bridesmaids. I need to know how nicely to go about them not being my bridesmaids anymore without upsetting my friends? Please help, I need to buy dresses soon????