Hello Hemanth,
Kindly do the following,
1.Shut-down or power off the virtual Machine
2.Right-Click the virtual Machine and select Migrate
3.Select a datastore to migrate the virtual machine other than the current datastore.
4.Select Type of virtual disk format from the drop-down option in select a virtual disk format
5.Click Next and Finish to complete the migration and disk format changes.
Suhas