is it not both?

create value because the windows have to be replaced and employees are paid for their labor in doing that.

destroy value bc they -1 inventory each time a window is broken

It's a net value loss. This is literally the parable of the broken window

https://en.wikipedia.org/wiki/Parable_of_the_broken_window

The fallacy is to think value was created by buying someone's labour to fix the window. This is value that's been displaced from something productive to something unproductive.

Instead of going from 0 to 1 (invest the money and create value), you went from -1 to 0 (spend money to fix the window to get back to where you were) and, overall, the value of a perfectly good window got lost.