The "forget" command:

Usage: fossil rm|delete|forget FILE1 ?FILE2 ...?

Remove one or more files or directories from the repository.

The 'rm' and 'delete' commands do NOT normally remove the files from
disk.  They just mark the files as no longer being part of the project.
In other words, future changes to the named files will not be versioned.
However, the default behavior of this command may be overridden via the
command line options listed below and/or the 'mv-rm-files' setting.

The 'forget' command never removes files from disk, even when the command
line options and/or the 'mv-rm-files' setting would otherwise require it
to do so.

WARNING: If the "--hard" option is specified -OR- the "mv-rm-files"
         setting is non-zero, files WILL BE removed from disk as well.
         This does NOT apply to the 'forget' command.

Options:
  --soft                  Skip removing files from the checkout.
                          This supersedes the --hard option.
  --hard                  Remove files from the checkout.
  --case-sensitive <BOOL> Override the case-sensitive setting.
  -n|--dry-run            If given, display instead of run actions.

See also: addremove, add