[InventoryService]
    LocalServiceModule = "OpenSim.Services.InventoryService.dll:XInventoryService"

    ; Will calls to purge folders (empty trash) and immediately delete/update items or folders (not move to trash first) succeed?
    ; If this is set to false then some other arrangement must be made to perform these operations if necessary.
    AllowDelete = false

If the php script only listens on your private subnet, take note that by default, llHttpRequest (which the terminal uses) can't request webpages from private subnets. There are two ways to address this:

Insecure: Remove your private subnet from the blacklist in OpenSim.ini:

[Network]
; 192.168.0.0/16 removed:
OutboundDisallowForUserScripts = 0.0.0.0/8|10.0.0.0/8|100.64.0.0/10|127.0.0.0/8|169.254.0.0/16|172.16.0.0/12|192.0.0.0/24|192.0.2.0/24|192.88.99.0/24|198.18.0.0/15|198.51.100.0/24|203.0.113.0/24|224.0.0.0/4|240.0.0.0/4|255.255.255.255/32

Caution, this would allow any lsl script (even in a visitor's attachment) to access any webserver in that private subnet, for example your NAS storage!

Secure: Use opensim-lickx instead of stock OpenSim. This (only) allows requests from the /lslhttp folder even on blacklisted private networks. See commit 7503d1a if you would like to apply this to your own OpenSim fork.

If the php script listens on the public ip (not recommended), ALLOWED_HOST should be filled in config.php, and the relevant section uncommented in trash.php.