Go to the Build\Android folder, and then create a new ManifestRequirementsOverride.xml file containing the permissions you’d like to override/remove.
For Example:
<uses-sdk android:minSdkVersion="21"/>
<uses-feature android:glEsVersion="0x00030001" android:required="true" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WAKE_LOCK"/>