[Permissions] Ensure defaults are cleared when clearing all rules (#3041)

- fixes #3037

redbot/core/commands/requires.py

@@ -398,11 +398,9 @@ class Requires:
         else:
             rules[model_id] = rule
 
-    def clear_all_rules(self, guild_id: int) -> None:
+    def clear_all_rules(self, guild_id: int, *, preserve_default_rule: bool = True) -> None:
         """Clear all rules of a particular scope.
 
-        This will preserve the default rule, if set.
-
         Parameters
         ----------
         guild_id : int
@@ -410,6 +408,12 @@ class Requires:
             `Requires.GLOBAL`, this will clear all global rules and
             leave all guild rules untouched.
 
+        Other Parameters
+        ----------------
+        preserve_default_rule : bool
+            Whether to preserve the default rule or not.
+            This defaults to being preserved
+
         """
         if guild_id:
             rules = self._guild_rules.setdefault(guild_id, _RulesDict())
@@ -417,7 +421,7 @@ class Requires:
             rules = self._global_rules
         default = rules.get(self.DEFAULT, None)
         rules.clear()
-        if default is not None:
+        if default is not None and preserve_default_rule:
             rules[self.DEFAULT] = default
 
     def reset(self) -> None: