The "unset" command:

Usage: fossil settings ?SETTING? ?VALUE? ?OPTIONS?
   or: fossil unset SETTING ?OPTIONS?

The "settings" command with no arguments lists all settings and their
values.  With just a SETTING name it shows the current value of that setting.
With a VALUE argument it changes the property for the current repository.

Settings marked as versionable are overridden by the contents of the
file named .fossil-settings/PROPERTY in the check-out root, if that
file exists.

The "unset" command clears a setting.

Settings can have both a "local" repository-only value and "global" value
that applies to all repositories.  The local values are stored in the
"config" table of the repository and the global values are stored in the
configuration database.  If both a local and a global value exists for a
setting, the local value takes precedence.  This command normally operates
on the local settings.  Use the --global option to change global settings.

Options:
  --global   set or unset the given property globally instead of
             setting or unsetting it for the open repository only.

  --exact    only consider exact name matches.

See also: configuration