I have read that you can burn pampas grass in order to get rid of the dead foliage.Will this kill the plant?
No it won't I can bet a bottom dollar on that. The flames are very quick and firey so be very careful if you do it. Nowhere near the house etc. Otherwise just get a saw or pruners and hack at it and tug the old stuff out. It will look awful for a little while but it soon comes back. Liz