deleting bad files

[Miller Sally S NPRI]

I am helping a team transition from RCS to CVS.
I did not create the repository but I would like to clean it up.
I am on a Unix system with a command line interface.
and want to delete  filename.c~

cvs remove -f filename.c~
but a cvs commit
tells me that the file is already locked by Common.

is there a way to remove the file by cvs or do I have to manually remove 
it in  the Repository.

TIA

Sally