[Chimera-users] make one chain from two chains ID in PDB

Hello, I'm working with a PDB file, in this file, one protein peptide was recognized as two chains (B and C), I want to make it as one chain, so it will be easier to do some interface analysis and modeling. I guess I can open the file as WORD file and change all the C to B one by one, but it's too much work to edit it that way. May I get some help for this? Is there a easier way to do this? Many thanks, Jianbo