Resetting a drop down menu by selecting another drop down menu

I'm still pretty inexperienced with Excel and I'm trying to figure out how if I change entries on a drop down menu it will clear out all other drop down menus based on that selection. IE, if I change the city from Houston to Dallas, the sub drop down menus would all be cleared out. I've attached a very dumbed down version of what I'm trying to accomplish. I'm pretty sure I will have to write something into macros and I have no idea how to do that. Any help would be greatly be appreciated. Thanks!

Using your example

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