Delete IIS logs

I'm trying to delete IIS logs that are older than 30 days from the current date.  

The following just deletes the 30th file from the current date. Just the one file.

Where did I go wrong:

cls

$PSRanFrom = Hostname

#

# Script to delete IIS log on Exchange servers.

#

# $Now = Get-Date -UFormat "%Y%m%d"

#$Now = "{0:yyyyMMdd}" -f [DateTime]::Now.AddDays(-1)

#$OldLogs = "{0:yyyyMMdd}" -f [DateTime]::Now.AddDays(-4) 

# Set $oldLogs back 20 days from now. 

$OldLogs = "u_ex{0:yyMMdd}" -f [DateTime]::Now.AddDays(-30) 

$ServerList = @("server","server","server","server")  

$Subject = "Deleted IIS Logs From Exchange Mailbox Server"

Foreach($Server in $ServerList){

        write-host "\\$Server\C$\inetpub\logs\LogFiles\W3SVC1\$OldLogs.log ... Copying."

        Remove-Item -Path \\$Server\c$\inetpub\logs\LogFiles\W3SVC1\$OldLogs.log -Force 

        write-host "\\$Server\c$\inetpub\logs\LogFiles\W3SVC1\$OldLogs.log ... Done."

    }

Send-mailmessage -SmtpServer yada.yada.com -from "someone@yada.com" -to "noone@yada.com" -subject $Subject -Body "Report of Exchange IIS Logs deleted from: $ServerList.   Script ran from: $PSRanFrom"