How can I stop the horde of zombies destroying my walls?

All the answers are costly. You can enter your base exactly when attack is happening and go near the zombies. They'll start following you and then get out of your base, they'll follow you out of your base.

You can slow them down or redirect them with traps. But if you can upgrade the walls to Level 3 then the zombies wont be able to destroy them.

You can use traps, traps are acquired through leveling up and then crafting them, otherwise you can just make your walls level 3 and they won't be able to damage them

There is a zombie called Witch in the infected forest. If you could kill it, you can take it's head. Place its head in your base to stop zombie horde from attacking. But a one head only works for few days. Then you will have to defeat the Witch again.!