Forum Link: https://forums.unrealengine.com/showthread.php?56056-My-first-Engine-modification-Blueprint-Lock-Node-feature

Am pretty excited today because I modified Engine source to add a feature I wanted. Its called Blueprint Lock Node feature. Basically what it does is, prevents the user from accidentally deleting any nodes.

Toggles lock mode via context menu

And you will see a Notification saying node is locked…

…so you cant delete it

If you want to delete that node then simply click on Toggle Lock again

This feature works for multiple nodes too