diff --git a/package.json b/package.json
index 290ea02c..d62d8c7a 100644
--- a/package.json
+++ b/package.json
@@ -244,7 +244,7 @@
         "vscode:prepublish": "npm run compile",
         "compile": "tsc -p ./",
         "watch": "tsc -watch -p ./",
-        "postinstall": "node ./node_modules/vscode/bin/install && node ./node_modules/leetcode-cli/bin/leetcode plugin -e leetcode.cn",
+        "postinstall": "node ./node_modules/vscode/bin/install",
         "test": "npm run compile && node ./node_modules/vscode/bin/test",
         "lint": "tslint --project tsconfig.json -e src/*.d.ts -t verbose"
     },
diff --git a/src/extension.ts b/src/extension.ts
index 715a4ad7..2605e52b 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -22,6 +22,8 @@ export async function activate(context: vscode.ExtensionContext): Promise<void>
     const leetCodeTreeDataProvider: LeetCodeTreeDataProvider = new LeetCodeTreeDataProvider(context);
 
     context.subscriptions.push(
+        leetCodeStatusBarItem,
+        leetCodeChannel,
         vscode.window.registerTreeDataProvider("leetCodeExplorer", leetCodeTreeDataProvider),
         vscode.commands.registerCommand("leetcode.deleteCache", () => cache.deleteCache()),
         vscode.commands.registerCommand("leetcode.toogleLeetCodeCn", () => plugin.toogleLeetCodeCn()),
@@ -45,6 +47,5 @@ export async function activate(context: vscode.ExtensionContext): Promise<void>
 }
 
 export function deactivate(): void {
-    leetCodeStatusBarItem.dispose();
-    leetCodeChannel.dispose();
+    // Do nothing.
 }
diff --git a/src/leetCodeChannel.ts b/src/leetCodeChannel.ts
index 16bb1262..fa32ac26 100644
--- a/src/leetCodeChannel.ts
+++ b/src/leetCodeChannel.ts
@@ -3,14 +3,7 @@
 
 import * as vscode from "vscode";
 
-export interface ILeetCodeChannel {
-    appendLine(message: any, title?: string): void;
-    append(message: any): void;
-    show(): void;
-    dispose(): void;
-}
-
-class LeetCodeChannel implements ILeetCodeChannel {
+class LeetCodeChannel implements vscode.Disposable {
     private readonly channel: vscode.OutputChannel = vscode.window.createOutputChannel("LeetCode");
 
     public appendLine(message: string): void {
@@ -30,4 +23,4 @@ class LeetCodeChannel implements ILeetCodeChannel {
     }
 }
 
-export const leetCodeChannel: ILeetCodeChannel = new LeetCodeChannel();
+export const leetCodeChannel: LeetCodeChannel = new LeetCodeChannel();
diff --git a/src/leetCodeExecutor.ts b/src/leetCodeExecutor.ts
index 45cf2306..3a656c5c 100644
--- a/src/leetCodeExecutor.ts
+++ b/src/leetCodeExecutor.ts
@@ -9,37 +9,7 @@ import { executeCommand, executeCommandWithProgress } from "./utils/cpUtils";
 import { DialogOptions } from "./utils/uiUtils";
 import * as wsl from "./utils/wslUtils";
 
-export interface ILeetCodeExecutor {
-    meetRequirements(): Promise<boolean>;
-    getLeetCodeBinaryPath(): Promise<string>;
-
-    /* section for cache command */
-    deleteCache(): Promise<string>;
-
-    /* section for user command */
-    getUserInfo(): Promise<string>;
-    signOut(): Promise<string>;
-    // TODO: implement login when leetcode-cli support login in batch mode.
-    // signIn(): Promise<string>;
-
-    /* section for problem command */
-    listProblems(showLocked: boolean): Promise<string>;
-    showProblem(id: string, language: string, outdir: string): Promise<string>;
-
-    /* section for session command */
-    listSessions(): Promise<string>;
-    enableSession(name: string): Promise<string>;
-    createSession(name: string): Promise<string>;
-
-    /* section for solution command */
-    submitSolution(filePath: string): Promise<string>;
-    testSolution(filePath: string, testString?: string): Promise<string>;
-
-    /* section for plugin command */
-    toggleLeetCodeCn(isEnable: boolean): Promise<string>;
-}
-
-class LeetCodeExecutor implements ILeetCodeExecutor {
+class LeetCodeExecutor {
     private leetCodeBinaryPath: string;
     private leetCodeBinaryPathInWsl: string;
 
@@ -142,4 +112,4 @@ class LeetCodeExecutor implements ILeetCodeExecutor {
     }
 }
 
-export const leetCodeExecutor: ILeetCodeExecutor = new LeetCodeExecutor();
+export const leetCodeExecutor: LeetCodeExecutor = new LeetCodeExecutor();
diff --git a/src/leetCodeManager.ts b/src/leetCodeManager.ts
index 5640b458..c61bc476 100644
--- a/src/leetCodeManager.ts
+++ b/src/leetCodeManager.ts
@@ -10,15 +10,7 @@ import { UserStatus } from "./shared";
 import { DialogType, promptForOpenOutputChannel } from "./utils/uiUtils";
 import * as wsl from "./utils/wslUtils";
 
-export interface ILeetCodeManager extends EventEmitter {
-    getLoginStatus(): void;
-    getStatus(): UserStatus;
-    getUser(): string | undefined;
-    signIn(): void;
-    signOut(): void;
-}
-
-class LeetCodeManager extends EventEmitter implements ILeetCodeManager {
+class LeetCodeManager extends EventEmitter {
     private currentUser: string | undefined;
     private userStatus: UserStatus;
 
@@ -123,4 +115,4 @@ class LeetCodeManager extends EventEmitter implements ILeetCodeManager {
     }
 }
 
-export const leetCodeManager: ILeetCodeManager = new LeetCodeManager();
+export const leetCodeManager: LeetCodeManager = new LeetCodeManager();
diff --git a/src/leetCodeStatusBarItem.ts b/src/leetCodeStatusBarItem.ts
index dab832a9..224a3536 100644
--- a/src/leetCodeStatusBarItem.ts
+++ b/src/leetCodeStatusBarItem.ts
@@ -4,12 +4,7 @@
 import * as vscode from "vscode";
 import { UserStatus } from "./shared";
 
-export interface ILeetCodeStatusBarItem {
-    updateStatusBar(status: UserStatus, user?: string): void;
-    dispose(): void;
-}
-
-class LeetCodeStatusBarItem implements ILeetCodeStatusBarItem {
+class LeetCodeStatusBarItem implements vscode.Disposable {
     private readonly statusBarItem: vscode.StatusBarItem;
 
     constructor() {
@@ -35,4 +30,4 @@ class LeetCodeStatusBarItem implements ILeetCodeStatusBarItem {
     }
 }
 
-export const leetCodeStatusBarItem: ILeetCodeStatusBarItem = new LeetCodeStatusBarItem();
+export const leetCodeStatusBarItem: LeetCodeStatusBarItem = new LeetCodeStatusBarItem();