Hi,
Yes you can rename VMFS or NFS datastore easily with the following steps
You can change the name of an existing datastore.
Procedure:
1 Display the datastores.
2 Right-click the datastore to rename and select Rename.
3 Type a new datastore name.
NOTE : If you use the vCenter Server system to manage your hosts, the new name appears on all hosts that have access to the datastore.