Okay - you seem to have a basic misunderstanding about this.
Windows is not installed on the motherboard, it's installed on the hard drive.
There is nothing to remove from the existing OEM motherboard.
However, after you install the new motherboard you will have to re-install Windows from scratch. The existing installation will not work on different hardware.
Ok haha I get it noww i was kind of confused about that because it would'nt really make sense for it to be on the mobo, thats just what I understood from different forums i'v read... So theres no way to NOT have to buy windows again?