Can I hold a horn by 1 valve cap and play a High F or G?
Can I play anything real with that little pressure?
You shouldn’t feel pain or soreness when playing or after playing.
You can NOT just stop using pressure.
You have to correct the reason that the pressure was needed first.
Then after you have a close set embouchure, good breathing habits and good muscle strength you can work on reducing pressure.
No pressure is NOT an option. LESS pressure is.
The lips produce compression by lip against lip movement. They also can control the aperture by pulling the corners in to play high. As a pressure player you never allowed your lips to do that AS the excessive pinned the lips in place and they couldn’t move enough to make compression. This is why the muscles must be worked first.
Play at a whisper. This works the lip aperture to aid in pressure reduction. This is one reason why the ENTIRE Clarke Technical studies book is marked pp-ppp.
You can open your left hand and stop grabbing the valves. The horn is now free to move some. Practice that way and you can reduce pressure.
Try a hand grip that I first wrote about 12 years ago. It helps you to use less pressure.
Don’t grab the horn and allow it to move slightly. Also don’t use the pinky ring with the right hand.