- In includes/Linker.php, make sure editSectionLinkForOther() and editSectionLink() return “”;
- In includes/Parser.php, around line with MAG_NOEDITSECTION, make sure $showEditLink is always set to 0
- In languages/Language.php, in the $wgDefaultUserOptionsEn array, make sure ‘editsection’ => 0
php maintenance/rebuildMessages.php --rebuild
Tested for 1.6, but may apply to other versions as well.