How can I uninstalled iOS 14 back to iOS 12

Because iOS 14.7 has bricked my iPhone 6S. The battery goes flat in about 1hr since I upgraded and battery health says it’s 92%. I’ve had other people check it and they say there is nothing wrong with the battery. When it was on 12.4 the battery lasted better than all day. Do you have a solution?

You can’t…..and why would you want to? Loads of apps would then stop working.

You can't.

AKRBTN didn’t answer dada 54s question he asked another one! Why is that that the Apple recommended answer? It wasn’t an answer!

How is it “not an answer”? Is it incorrect?