Corrigindo metodo adicionado indevidamente na interface

.idea/workspace.xml

@@ -2,7 +2,7 @@
 <project version="4">
   <component name="ChangeListManager">
     <list default="true" id="c86c4633-af9b-40bd-8d75-715dd99b9de1" name="Default Changelist" comment="">
-      <change afterPath="$PROJECT_DIR$/src/OperacaoRaiz.java" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/Operacao.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/Operacao.java" afterDir="false" />
     </list>
     <ignored path="$PROJECT_DIR$/out/" />
     <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
@@ -21,11 +21,13 @@
       </usages-collector>
       <usages-collector id="statistics.file.extensions.open">
         <counts>
+          <entry key="iml" value="1" />
           <entry key="java" value="4" />
         </counts>
       </usages-collector>
       <usages-collector id="statistics.file.types.open">
         <counts>
+          <entry key="IDEA_MODULE" value="1" />
           <entry key="JAVA" value="4" />
         </counts>
       </usages-collector>
@@ -52,11 +54,11 @@
           </provider>
         </entry>
       </file>
-      <file pinned="false" current-in-tab="true">
+      <file pinned="false" current-in-tab="false">
         <entry file="file://$PROJECT_DIR$/src/OperacaoRaiz.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="30">
-              <caret line="2" column="34" selection-start-line="2" selection-start-column="34" selection-end-line="2" selection-end-column="34" />
+            <state relative-caret-position="75">
+              <caret line="5" lean-forward="true" selection-start-line="5" selection-end-line="5" />
               <folding>
                 <element signature="e#92#93#0" expanded="true" />
                 <element signature="e#124#125#0" expanded="true" />
@@ -74,11 +76,11 @@
           </provider>
         </entry>
       </file>
-      <file pinned="false" current-in-tab="false">
+      <file pinned="false" current-in-tab="true">
         <entry file="file://$PROJECT_DIR$/src/Operacao.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="15">
-              <caret line="1" column="4" selection-start-line="1" selection-start-column="4" selection-end-line="1" selection-end-column="44" />
+            <state relative-caret-position="45">
+              <caret line="3" lean-forward="true" selection-start-line="3" selection-end-line="3" />
             </state>
           </provider>
         </entry>
@@ -99,6 +101,7 @@
     <option name="CHANGED_PATHS">
       <list>
         <option value="$PROJECT_DIR$/src/OperacaoRaiz.java" />
+        <option value="$PROJECT_DIR$/src/Operacao.java" />
       </list>
     </option>
   </component>
@@ -145,7 +148,7 @@
   <component name="PropertiesComponent">
     <property name="WebServerToolWindowFactoryState" value="false" />
     <property name="aspect.path.notification.shown" value="true" />
-    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1535380549562" />
+    <property name="com.android.tools.idea.instantapp.provision.ProvisionBeforeRunTaskProvider.myTimeStamp" value="1535381335232" />
     <property name="nodejs_interpreter_path.stuck_in_default_project" value="undefined stuck path" />
     <property name="nodejs_npm_path_reset_for_default_project" value="true" />
   </component>
@@ -171,12 +174,12 @@
       <option name="number" value="Default" />
       <option name="presentableId" value="Default" />
       <updated>1535380253968</updated>
-      <workItem from="1535380258971" duration="245000" />
+      <workItem from="1535380258971" duration="692000" />
     </task>
     <servers />
   </component>
   <component name="TimeTrackingManager">
-    <option name="totallyTimeSpent" value="245000" />
+    <option name="totallyTimeSpent" value="692000" />
   </component>
   <component name="ToolWindowManager">
     <frame x="0" y="0" width="1440" height="900" extended-state="6" />
@@ -219,6 +222,9 @@
     <option name="myLimit" value="2678400000" />
   </component>
   <component name="editorHistoryManager">
+    <entry file="file://$PROJECT_DIR$/minicurso.iml">
+      <provider selected="true" editor-type-id="text-editor" />
+    </entry>
     <entry file="file://$PROJECT_DIR$/src/Calculadora.java">
       <provider selected="true" editor-type-id="text-editor">
         <state relative-caret-position="30">
@@ -233,17 +239,10 @@
         </state>
       </provider>
     </entry>
-    <entry file="file://$PROJECT_DIR$/src/Operacao.java">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="15">
-          <caret line="1" column="4" selection-start-line="1" selection-start-column="4" selection-end-line="1" selection-end-column="44" />
-        </state>
-      </provider>
-    </entry>
     <entry file="file://$PROJECT_DIR$/src/OperacaoRaiz.java">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="30">
-          <caret line="2" column="34" selection-start-line="2" selection-start-column="34" selection-end-line="2" selection-end-column="34" />
+        <state relative-caret-position="75">
+          <caret line="5" lean-forward="true" selection-start-line="5" selection-end-line="5" />
           <folding>
             <element signature="e#92#93#0" expanded="true" />
             <element signature="e#124#125#0" expanded="true" />
@@ -251,5 +250,12 @@
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/src/Operacao.java">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="45">
+          <caret line="3" lean-forward="true" selection-start-line="3" selection-end-line="3" />
+        </state>
+      </provider>
+    </entry>
   </component>
 </project>
\ No newline at end of file

src/Operacao.java

 public interface Operacao {
     public double opera(double x, double y);
-    
-    public double OperacaoMult(double x, double y)
-    {
-        return x * y;
-    }
 }