How to add "stop charging" button?

[NoisyBoy1308]

I am quite new to HA and my coding skills are below zero. As I cant control my wallbox directly and cannot use evcc, I am working on aworkaround via PSACC. My idea is, that HA will stop charging the car, when the House battery level drops below a certain point. But I cannot figure out, how to add a command that will be sent to the car, so it stops charging. Can someone point me in the right direction?