Navigate to the SharePoint list, in the ribbon interface click on List tab. In the Settings group, click on List Settings. In the Permissions and Management section, click on Pemissions for this list. You could be able to view all the permissions for the list.

Steps Involved:

  1. Open SharePoint 2010 Management Shell by going to Start | All Programs | SharePoint | Microsoft SharePoint 2010 Products | SharePoint 2010 Management Shell (Run as Administrator).
  2. Run the following script.

Powershell Script:

 
 
## Remove user permission from SharePoint 2010 list using web service in powershell
$uri="http://serverName:10736/sites/ECT2/_vti_bin/Permissions.asmx?wsdl" 
## $listName is a string which contains the list name from which user permission has to be removed
[String]$listName="A1"
## $type is a string which contains the object type - List
[String]$type="List"

## $permissionIdentified is a string which contains the user (domainName\UserName) for whom the permission has to be removed
[String]$permissionIdentifier="domainName\userName"

## $permissionType is a string which contains the permission type - user
[String]$permissionType="user"

## Web Service Reference - http://Site/_vti_bin/Permissions.asmx
$permissionWebServiceReference = New-WebServiceProxy -Uri $uri -UseDefaultCredential 
$permissionWebServiceReference.RemovePermission($listName,$type,$permissionIdentifier,$permissionType)