How to reset pagination and gridpanel using extjs

If pagination on grid is on bottom toolbar then use the following code 

Ext.getCmp('gridId').getStore().removeAll();

Ext.getCmp('gridId').getBottomToolbar().updateInfo(); 

If pagination on grid is on top toolbar then use the following code  

Ext.getCmp('gridId').getStore().removeAll();

Ext.getCmp('gridId').getTopToolbar().updateInfo();