The purpose of this note is to investigate the use of a metallic pipe with small corrugations for passively dechirping, through its wakefield, the LCLS beam. Similar dechirper systems have been tested in Pohang and Brookhaven at relatively low energies (< 100 MeV) and with relatively long bunches (> 1 ps). A recent proposal from RadiaBeam is to build a 2-m dechirper and install it in the LCLS for a GeV, femtosecond beam test. Such a device can be used to either reduce or increase the amount of energy chirp in a short electron bunch prior to the FEL interaction in the undulator, and hence provide a flexible control of the LCLS FEL bandwidth. The results can be used to guide the design of the LCLS-II dechirper, where it is important to remove unwanted electron energy chirp from the LCLS-II superconducting accelerator and to provide independent controls of x-ray properties in each of the two parallel beamlines. Show Partial Abstract