AddMember

Check membership

PS C:\> Get-ADGroup -Identity "NC Agents" -Properties * | Select -ExpandProperty Members

Adding user to group

PowerView Required!

PS C:\> Add-DomainGroupMember -Identity 'NC Agents' -Members 'songbird' -Credential $Cred -Verbose

Deleting user from group

PS C:\> Remove-DomainGroupMember -Identity "NC Agents" -Members 'songbird' -Credential $Cred -Verbose