Click on the System and Maintenance link.
Note: If you’re viewing the Classic View of Control Panel, you won’t see this link. Simply double-click on the Administrative Tools icon and skip a step.
Click on the Administrative Tools link.
In the Administrative Tools window, open the Computer Management program.
In the Computer Management window, locate the Disk Management option on the left and left-click on it.
If the Disk Management option is not visible, look under the Storage option by clicking the small arrow next to the word Storage.
On the right-hand side of the screen, locate and right-click on the drive that you wish to change the drive letter of and choose Change Drive Letter and Paths….