yes and no: if you want to lock them in your office/workplace and the files are on the server, work with your IT to grant/remove read-write-delete access for others.
If you want to lock DWG files outside of your office, ask yourself: is the recipient so stupid they will accept locked DWG files from you with no questions asked and they will not demand unlocked files (as opposed to PDFs or DWFs or something other raster image option)? if you answered yes, have a credit card handy and buy CADLOCK (website of the same name) and remember to walk your recipients through the hoops they need to access your files. There is no free solution for you that would not work to unlock the files for others.
Enjoy.