The absence of entrances will increase the level of difficulty and make the gameplay more satisfying. By rethinking this concept, we can create a unique and memorable experience.

spawn some walls or rocks infrount of them.

Razor

spawn some walls or rocks infrount of them.

Could you please help me with how to remove the entrance markers in the tunnels?

2pa777

Could you please help me with how to remove the entrance markers in the tunnels?

You would need a custom map or edit the map with rustedit.

Personally, I wouldn't worry about the tunnel being marked on the map.  You could use Sign Artist and post a Under Construction Image (pulled from images.google).  I'm not sure how you would build over the monument unless you have ubertool.  If not, you could use Edit Tool (UMod) and copy/paste a large building entity like something from Abandoned Military Tunnle, blocking the entrance.