Q.Hellebores
Should I prune leaves of an evergreen hellebore which are still green and not brown?

Midwinter is a good time to prune away the old leaves from the exterior of the plant. Hellebores start to form their buds in midwinter, so watch so you don't clip new growth.
Use clippers and wear gloves to protect from the thorns.
Dead head the blossoms throughout the blooming time to encourage more flowering.
Hellebores are quite forgiving and can be light pruned anytime of year to clean up the plants.
https://www.gardeningknowhow.com/ornamental/flowers/hellebore/growing-hellebores.htm