If you would like to rename a service application or it's proxy, PowerShell can get it done!

Let's say the Managed Metadata service is named "Managed Metadata" and the associated proxy is also named "Managed Metadata".  To change the service name to "Managed Metadata Service" and the proxy name to "Managed Metadata Service Proxy", the following script would do it:

# Rename SharePoint Service Application
$service = Get-SPServiceApplication -Name "Managed Metadata"
$service.Name = "Managed Metadata Service"
$service.Update()

# Rename SharePoint Service Application Proxy
$proxy = Get-SPServiceApplicationProxy | ? {$_.Name -eq "Managed Metadata"}
$proxy.Name = "Managed Metadata Service Proxy"
$proxy.Update()