Writing documentation is difficult. Make it too terse, and people will complain that they don’t understand. Make it too verbose, and people will stop reading it or get confused because the same thing is said several times with different words.
As in this suggested improvement, which I don’t think is one:
It removes them. They’re gone. Consequently, they don’t exist any longer. Adding “from the Tags section” is not helpful, as that implies they might still exist elsewhere. Which they dont.
Which begs the question what an “original item” is – I doubt that it refers to the originality of the content, so what does “original” mean here? Personally, I don’t think of a tag “referencing a document”, but rather of a tag being “attached” to a document. That concept translates to “the tags are removed from all documents they’re attached to”, avoiding the complicated grammar with two "that"s.
That’s overly verbose (“the same action” instead of “the same”, “of any database” is not helpful – if it’s any, there’s no need to mention databases at all), the sentence is far too long, it introduces weird terms (“source item” – is that the same as an “original document”? But why “source” then – no document is the “source” of a tag).
One would have to read through a lot of stuff to understand a simple concept:
If you delete a tag, it is removed from the database and from all documents it was attached to. Those documents remain otherwise untouched.