How to give rights to one user for the restart of a service

You can use the sc command to set permissions on a specific service.
The format is a little difficult to understand, but first you will need to find the user or group's SID to use the command (something like "S-1-5-21-....").

sc myserver sdset spooler D:(A;;RPWP;;;place-sid-here)

A couple notes on that command:

• RP Allows service start
• WP Allows service stop