There are two ways how you can unlink user and driver accounts and they are described bellow. Choose which is more suitable or convenient for you.
Unlink User in the Drivers section
Open the Driver management section and switch to the Drivers
Click Edit of the relevant driver to open driver's profile
Switch to the 'User account' tab and unclick in the checkbox 'Link to user'
Click SAVE to finish unlinking
Unlink Driver in the Users section
Go to Settings >> Users to open the user management section
Find the necessary user and click the Edit button to proceed with unlinking
In the pop-up window, in the 'Profile settings' tab find the 'Linked driver'
In the dropdown list select option 'No linked driver' to unlink current driver from the user
Click SAVE to finish unlinking
🔔 Keep in mind! If the linkage is removed, the driver will retain access to all vehicles the user had access to.