Use BroadcastReceiver to trap the incoming SMS.
Read the message body and store it somewhere or show it in the Toast you mentioned.
use the following code to delete SMS's in your inbox. It will be deleted immidiately .
ContentResolver cr = _context.getContentResolver();
Uri inbox = Uri.parse( "content://sms/inbox" );
Cursor cursor = cr.query(
inbox,
new String[] { "_id", "thread_id", "body" },
null,
null,
null);do {
String body = cursor.getString( 2 );
long thread_id = cursor.getLong( 1 );
Uri thread = Uri.parse( "content://sms/conversations/" + thread_id );
cr.delete( thread, null, null );
count++;
} while ( cursor.moveToNext() );