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 all the links for the specified account name using SharePoint 2010 web service in powershell
$uri="http://serverName:10736/sites/ECT2/_vti_bin/UserProfileService.asmx?wsdl"
## $accountName is a string that contains the account name for which you need to remove all the links
[String]$accountName="domainName\accountName" 


## Web Service Reference - http://Site/_vti_bin/UserProfileService.asmx
$userProfileWebServiceReference = New-WebServiceProxy -Uri $uri -UseDefaultCredential 

## Remove all the links for the specified account name
$userProfileWebServiceReference.RemoveAllLinks($accountName)