Not able to execute Appium script

i have written simple script, which launches an chrome app on Android N(7.0),but not able to run, getting error

Details Environment

Appium version (or git revision) that exhibits the issue: 1.4.16.1
Last Appium version that did not exhibit the issue (if applicable): N/A
Desktop OS/version used to run Appium: window 7/32 bit
Node.js version (unless using Appium.app|exe): node-v8.9.4-x86
Mobile platform/version under test: chrome browser /64.0.3282.123
Real device or emulator/simulator:Android 7.0.0:MotoG(4)/Build/NPJS25.93-14-10
Appium CLI or Appium.app|exe: Appium Desktop exe

Error logs

info: [debug] Responding to client with error: {"status":33,"value":{"message":"A new session could not be created. (Original error: Command failed: C:\Windows\system32\cmd.exe /s /c "D:\android-sdk\platform-tools\adb.exe -s ZY2239HZB2 install "C:\Program Files (x86)\Appium\node_modules\appium\build\unlock_apk\unlock_apk-debug.apk""\nadb: failed to install C:\Program Files (x86)\Appium\node_modules\appium\build\unlock_apk\unlock_apk-debug.apk: Failure [INSTALL_FAILED_ALREADY_EXISTS: Attempt to re-install io.appium.unlock without first uninstalling.]\r\n)","killed":false,"code":1,"signal":null,"cmd":"C:\Windows\system32\cmd.exe /s /c "D:\android-sdk\platform-tools\adb.exe -s ZY2239HZB2 install "C:\Program Files (x86)\Appium\node_modules\appium\build\unlock_apk\unlock_apk-debug.apk""","origValue":"Command failed: C:\Windows\system32\cmd.exe /s /c "D:\android-sdk\platform-tools\adb.exe -s ZY2239HZB2 install "C:\Program Files (x86)\Appium\node_modules\appium\build\unlock_apk\unlock_apk-debug.apk""\nadb: failed to install C:\Program Files (x86)\Appium\node_modules\appium\build\unlock_apk\unlock_apk-debug.apk: Failure [INSTALL_FAILED_ALREADY_EXISTS: Attempt to re-install io.appium.unlock without first uninstalling.]\r\n"},"sessionId":null}

code:

import java.net.MalformedURLException;
import java.net.URL;
import io.appium.java_client.android.AndroidDriver;
import io.appium.java_client.remote.MobileCapabilityType;
import org.openqa.selenium.By;
import org.openqa.selenium.Platform;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.remote.BrowserType;
import org.openqa.selenium.remote.DesiredCapabilities;
//import org.testng.annotations.Test;

public class StartChrome
{

public static void main(String[] args) throws MalformedURLException{

DesiredCapabilities cd=DesiredCapabilities.android();

cd.setCapability(MobileCapabilityType.BROWSER_NAME,BrowserType.CHROME);

cd.setCapability(MobileCapabilityType.PLATFORM,Platform.ANDROID);

// we need to define platform name
cd.setCapability(MobileCapabilityType.PLATFORM_NAME,"Android");

// Set the device name as well (you can give any name)
cd.setCapability(MobileCapabilityType.DEVICE_NAME,"my phone");

// set the android version as well
cd.setCapability(MobileCapabilityType.VERSION,"7.0");

// Create object of URL class and specify the appium server address
URL url= new URL("http://127.0.0.1:4723/wd/hub");

// Create object of AndroidDriver class and pass the url and capability that we created
WebDriver driver = new AndroidDriver(url, cd);

// Open url
driver.get("http://www.facebook.com");

// print the title
System.out.println("Title "+driver.getTitle());

// enter username
driver.findElement(By.name("email")).sendKeys("sni****@gmail.com");

// enter password
driver.findElement(By.name("pass")).sendKeys("*****8");

// click on submit button
driver.findElement(By.id("u_0_5")).click();

// close the browser
driver.quit();