It happened me way to often I was trying to chat with someone while I had the town center selecter. I touched the delete button by mistake and POOF! Bye town center. Every time I feel like a fool and my team hates me for it. I even had games where I just pulled the delete key from my keyboard.

I've seen that DE has implemented a warning when you delete important buildings and units. Isn't it possible to implement this in the Voobly version as well?

I have delete as a thumb button on my mouse so I can delete very fast.
So I am not a fan of your suggestion, unless it's an option that you can turn off...

On DE it's optional, yes. (default activated)

That's hard to do. We'd have to catch the key stroke, confirm it is a delete order and check the unit/building it is targeting.