[Become superuser on a node and place the node to be removed in maintenance state.]
[Determine the quorum device to be removed:]
# scconf -pv | grep Quorum
[Execute the scsetup utility:]
# scsetup
[Select option 1:]
*** Main Menu ***
    Please select from one of the following options:
      1) Quorum
       ...
    Option:  1
[Select option 2:]
*** Quorum Menu ***
    Please select from one of the following options:
       ...
      2) Remove a quorum disk
       ...
    Option:  2
[Answer the questions when prompted:]
 >>> Remove a Quorum Disk <<<
    ...
    Is it okay to continue (yes/no) [yes]? <Return>
    Which quorum disk do you want to remove (d<N>)?  d4
    Is it okay to proceed with the update (yes/no) [yes]? <Return>
 
scconf -r -q globaldev=d4
 
    Command completed successfully.
    Hit ENTER to continue: 
[Quit the scsetup Quorum Menu and Main Menu:]
    ...
    Option:  q
[Verify the quorum device is removed:]
# scstat -q
 
-- Quorum Summary --
 
  Quorum votes possible:      3
  Quorum votes needed:        2
  Quorum votes present:       3
 
-- Quorum Votes by Node --
 
                    Node Name           Present Possible Status
                    ---------           ------- -------- ------
  Node votes:       phys-schost-1       1        1       Online
  Node votes:       phys-schost-2       1        1       Online
 
-- Quorum Votes by Device --
 
                 Device Name         Present Possible Status  Owner
                 -----------         ------- -------- ------  -----
  Device votes:  /dev/did/rdsk/d3s2  1        1       Online  phys-schost-1