chain: simplify deleteRwSettings code and improve it's doc

Co-authored-by: Ryan Ofsky <ryan@ofsky.org>

src/interfaces/chain.h

@@ -369,6 +369,8 @@ public:
     virtual bool overwriteRwSetting(const std::string& name, common::SettingsValue value, SettingsAction action = SettingsAction::WRITE) = 0;
 
     //! Delete a given setting in <datadir>/settings.json.
+    //! This method provides a simpler alternative to overwriteRwSetting when
+    //! erasing a setting, for ease of use and readability.
     virtual bool deleteRwSettings(const std::string& name, SettingsAction action = SettingsAction::WRITE) = 0;
 
     //! Synchronously send transactionAddedToMempool notifications about all

src/node/interfaces.cpp

@@ -841,10 +841,7 @@ public:
     }
     bool deleteRwSettings(const std::string& name, interfaces::SettingsAction action) override
     {
-        args().LockSettings([&](common::Settings& settings) {
-            settings.rw_settings.erase(name);
-        });
-        return action != interfaces::SettingsAction::WRITE || args().WriteSettingsFile();
+        return overwriteRwSetting(name, {}, action);
     }
     void requestMempoolTransactions(Notifications& notifications) override
     {