You can achieve this by hiding the hamburger button. Set your toolbar navigation icon to null.
toolbar.setNavigationIcon(null);
EDIT
To remove the navigation icon, add the following line in your onCreate
method.
getActionBar().setDisplayHomeAsUpEnabled(false);
or
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
getSupportActionBar().setHomeButtonEnabled(false);
To make the SearchView fill the action bar, set the width of the SearchView to max in the onCreateOptionsMenu
method.
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_search, menu);
SearchView searchView =
(SearchView)menu.findItem(R.id.menu_search).getActionView();
searchView.setMaxWidth(Integer.MAX_VALUE);