Powershell to get- every subsite in farm

(Powershell noob here)  I'm attempting to write a script to delete every /SitePages/Results.aspx file in the farm, but only for SubSites.  So far i've got this, which gives me each site in the farm, but i only want to do this on subsites.

$sites= Get-SPSite -WebApplication $url|Where-Object{$_.Url -like"$url/sites/*"}
foreach($site in $sites){
# Delete fuctions here.
}