Hey! Easiest way: o.unload Shop, delete that players file under oxide/data/Shop/Players/ (named by their steam id), then o.load Shop. Works whether theyre online or not since the unload flushes everything from memory first, just a few seconds of downtime for everyone. If you want zero downtime, make sure that player is offline, delete their file, and skip the reload, the shop reads it fresh when they reconnect.
On the ID field, thats just an internal id the shop uses to tell items apart, its NOT the Rust item id. The actual Rust item comes from ShortName. So for Item type you can leave ID at 0 and for Command type the same, the plugin assigns it automatically. Your current config is fine, you just had the meaning of that field a bit off.