How do I destroy village banners?

[Eraldo03]

Note that I don't belong to the said village and that it's abandoned.

[Kaios]

Depends, if they are your own banners and you're either the lawspeaker or someone who has been given the appropriate permissions you can destroy them by hand. If they belong to another village you can use a siege machine to destroy them if the village still has authority, if the authority is drained you can destroy them by hand as well.