Not been able to navigate to login screen , after logout.

Your root-level navigation should be a StackNavigator with children looking something like this:

• Welcome screen
• Login screen
• Tab Navigator (for logged in home screen)
  • Tab 1
  • Tab 2
  • Tab 3
  • Tab 4 (with logout button)

To reset the TabNavigator, you shouldn't dispatch an action of type NavigationActions.NAVIGATE because that will push onto the current navigation stack, instead of removing the tab navigator from the state. Instead, consider using a Reset action. So the code within your logout function should have:

const resetAction = NavigationActions.reset({
  index: 0,
  actions: [
    NavigationActions.navigate({ routeName: 'Login'})
  ]
})
this.props.navigation.dispatch(resetAction);

onPress of Logout we are calling below code

  const resetAction = NavigationActions.reset({
  index: 0,
  actions: [NavigationActions.navigate({ routeName: "SignIn" })],
    key: null 
  });
  this.props.navigation.dispatch(resetAction);

This is our AppNavigation file is there any way to reset app on Logout

const PrimaryNav = StackNavigator(
  {
    SignIn: {
      screen: SignIn,
      navigationOptions: {
        headerMode: "none",
        header: null
      }
    },
    SignUp: {
      screen: SignUp,
      navigationOptions: {
        headerMode: "none",
        header: null
      }
    },
    TabsScreen: {
      screen: TabsScreen,
      navigationOptions: {
        headerMode: "float",
        headerTitleStyle: { color: "#ffffff" },
        gesturesEnabled: true,
        header: null,
      }
    },
)
export const sideMenuStack = StackNavigator({
    SideMenu: {
        screen: SideMenu,
        navigationOptions: {
            headerMode: "none",
            header: null
        }
    },
    Settings: {
        screen: Settings,
        navigationOptions: ({ navigation }) => ({
            title: "Settings",
        })
    },
    SignIn: {
      screen: SignIn,
      navigationOptions: {
        headerMode: "none",
        header: null
      }
    },
)
export const FeedsStack = StackNavigator({
    FeedsStack: {
        screen: FeedsStack,
        navigationOptions: {
            headerMode: "none",
            header: null
        }
    },
    Post: {
        screen: Post,
        navigationOptions: ({ navigation }) => ({
            title: "Post",
        })
    },
)
export const UserStack = StackNavigator({
    UserStack: {
        screen: UserStack,
        navigationOptions: {
            headerMode: "none",
            header: null
        }
    },
    Friends: {
        screen: Friends,
        navigationOptions: ({ navigation }) => ({
            title: "Friends",
        })
    },
)
export const TabView = TabNavigator(
  {
    FeedsStack: {
      screen: FeedsStack,
      navigationOptions: {
        tabBarLabel: "Feeds",
        scrollEnabled: true,
        focussed: true,
        tabBarIcon: ({ tintColor }) =>
          <Image
            source={Images.feedsActive}
            style={[styles.icon, { tintColor: tintColor }]}
          />
      }
    },
    UserStack: {
      screen: UserStack,
      navigationOptions: {
        tabBarLabel: "Users",
        tabBarIcon: ({ tintColor }) =>
          <Image
            source={Images.UserActive}
            style={[styles.icon, { tintColor: tintColor }]}
          />
      }
    },
    sideMenuStack: {
      screen: sideMenuStack,
      navigationOptions: {
        tabBarLabel: "More",
        headerMode: "screen",
        tabBarIcon: ({ tintColor }) =>
          <Image
            source={Images.moreActive}
            style={[styles.icon, { tintColor: tintColor }]}
          />
      }
    }
  },
  //Default configurations for Tabs
  {
    tabBarPosition: "bottom",
    animationEnabled: true,
    tabBarOptions: {
       indicatorStyle:{
        borderBottomColor:'#32a1fe',
        borderBottomWidth:3
      },
      showLabel: true,
      backBehavior: "none",
      showIcon: true,
      activeTintColor:"#338AD8",
      inactiveTintColor:"#BEC5CB",
      upperCaseLabel:false,
      labelStyle :[styles.labelStyle],
    }
  }
);