Normally, when you hit "Remove" option on your post, it'll disappear on topic and your post count decreases. But it doesn't mean that your post was completely deleted. In fact, it was moved to "Trash" (can imagine that "Trash" is similar to "Recycle Bin" in Windows). You and other people still can see it in your post history. Here's an example:
Before delete:

After delete:

Still appear on your post history:
How to make it gone for good?
On your post history, right click on the title: "Trash / Re: Altcointalks Forum In 2020", choose "Open link in new tab" to see its location on "Trash". Click on "Remove" again and it'll be gone forever.