Since you’ve not defoliated before, you want to start slow and only take a few leaves off at a time. To start you want to take 3-5 fan leaves and take the ones blocking bud sites. Wait a few days and take a few more. Look at the top of the plant from where the light would be shining down on it and you should see which leaves are blocking bud sites.
Alternatively since you’re already halfway through flower you can also not defoliate and continue the grow as is.