In dewiki, we wanted to hide the line Add watchlist labels to help organise how you review changes to Wikipedia (MediaWiki:Watchlistlabels-editpage-help), as all information can be found in the help page linked in the preceding label (MediaWiki:watchlistlabels-editpage-label).

First, we tried -, which is usually used to hide such interface messages, but the hyphen was directly shown in the editing form. Then we tried <span style="display:none">-</span>, which worked for the old source editor, but was not processed in the editing form of VE and NWE. Right now, we are using an nbsp as temporary solution, but that leaves an ugly empty line under the watchlist label selection.

For better local configuration, could the interface message be changed to accept a - for deactivating it?