How to reduce tension in my swing

The solution here is practice, tension is rooted in your mental approach and your practice.

You need to rehearse getting over the ball tension free, hitting balls without consequence and focussing just on a feather light grip. You will soon see you don’t need a death grip to hit a good shot.

Practice your grip whenever you can, making sure its light and tension free.

When you eventually step on the tee you can confidently grip lightly.

No practice will just mean tension returns once you stop consciously thinking “no tension”.