how can i delete my first post here ?

In general, users here have about 15 minutes to make edits on their post after submitting. A pencil icon will be visible below the post, to initiate editing mode. After that time, the post stays as-is, unless the Hosts intervene.

You may always add a reply with new information or correcting information, as needed.

For things that should not be posted at all, users may alert the Hosts through the (!) icon at the lower right for each post. Any report through there is a request, that can be granted or denied by them, so use it sparingly for when really needed.

We can, on your behalf, ask the Mods ("Hosts") to edit your post. Would that take case of the issue?

It appears from your subscription page:

Crystallilly’s Subscriptions - Apple Community

that you double-posted. Is that the issue? We can also ask that duplicate posts be resolved.

[FYI: When you get to Level 3, you gain reporting privileges and can report yourself.]