As i understand you, You are classifying an existing tunnel (fake) as something that is not worthy of beeing shown on the map. Even though it maybe not passable or maybe it is passable, which would need to be determinated. You can still let it be present with access=no, and when someone shows up with the evidence of going through it, then that person could change it to access=yes. Or if this is not acceptable, then mark it as railway=abandoned. But it is Unacceptible for an existing structure to not be present on the map! Because now i only see the Negation of an existing structure (because it is removed). These excedes some ethical principles which i do not want to be part of. (The 'G' was only source that could be found, (Even though i admit that really it is my fault, not deffining it as access=no, or railway=abandoned, to not misleed someone through unintentionaly. For that i appologise!) 

P.S. May somebody from Valjevo, who sees this comment, go and explore Tunel Brđani, and determinate if you can go through it or not. 
-At this moment i am not able to visit the location and document.