Manage Web Application Policy using SharePoint PowerShell Script

Remove a existing Web Application Policy using SharePoint PowerShell Script

# Get the Web Application Object
$webappobj = Get-SPWebApplication [Web Application URL]

# Return the Web Application policies and find the index of the policy which you would like to delete
$webappobj.Policies

# Put the index value and delete the policy
$webappobj.Policies.Remove([Index])

$webappobj.Update()

# Verify the policies again if it is deleted successfully
$webappobj.Policies

Add a new Web Application Policy using SharePoint PowerShell Script

# Get the Web Application Object
$webappobj = Get-SPWebApplication [Web Application URL]

# Create a policy role object with permission level like FullRead, FullControl etc.
$fullReadPolicyRole = [Microsoft.SharePoint.Administration.SPPolicyRoleType]::FullRead
$policyRole = $webappobj.PolicyRoles.GetSpecialRole($fullReadPolicyRole)

# Add the new web app policy with account name and account description
$policy = $webappobj.Policies.Add("TECHMM\SSWAIN", "Samarendra Swain")

# Bind the policy role to the new web  app policy
$policy.PolicyRoleBindings.Add($policyRole)

$webappobj.Update()