You can do this with autohotkey.
Link to my previous message about this.
Just repeat the same for all windows. e.g.
Example to remove border on first 2 widows:
The downside is that you would need to know a bit about AHK to make this work.Code:WinSet, Style, -0xC40000, ahk_id %WowWinId1% ;1st window WinSet, Style, -0xC40000, ahk_id %WowWinId2% ;2nd window
Connect With Us