CACLS files /e /p {USERNAME}:{PERMISSION}

Where,

• /p : Set new permission
• /e : Edit permission and kept old permission as it is i.e. edit ACL instead of replacing it.
• {USERNAME} : Name of user
• {PERMISSION} : Permission can be:
  • R – Read
  • W – Write
  • C – Change (write)
  • F – Full control

For example grant Rocky Full (F) control with following command (type at Windows command prompt):

C:> CACLS files /e /p rocky:f

Read complete help by typing following command:

C:> cacls /?

Quelle: Windows change access permissions from the command line