Controlling Design History Settings
The MS_DESIGN_HISTORY configuration variable provides options to control how design history can be used. By default, the create, commit, browse, tag, set version format, and set version capabilities are enabled, and the delete, change description, change author, combine, retire, and automatic upgrade capabilities are disabled.
Generally, you should not change the default settings. In particular, use caution in deleting the design history for a file, since it cannot be recovered. Rather than deleting the design history, you can copy the contents of the file to a new file that does not contain the design history. Removing history from the current file is almost never necessary, except in cases where the file is so large that you cannot open it in order to make a copy without history.
If you must delete the design history for the current file, use the following procedure.