I added `android:theme="@android:style/Theme.NoTitleBar"` to the manifest file but the app doesn't open. I want to remove the `Activity` label in which the name of the `Activity` is written.

> 
> Here is part of manifest file:
> 
> 
> 

```
    <application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.NoTitleBar"
    >

```