How to Prune carnation sedge?
No pruning required, tidy if possible as the foliage dies down at the end of the growing season

carnation sedge · Carex panicea
Tolerant of a wide range of growing conditions in full sun or part shade. Grow in waterside locations, boggy or wet soils and any moist but well drained or well-drained soils. See ornamental grasses cultivation, bog gardening and pond plants
No pruning required, tidy if possible as the foliage dies down at the end of the growing season