What about the system window security lock?

It can be disassembled at the handle and then unscrewed with a flat screwdriver.

Check first to make sure the window is unlocked. If it is locked, pry it open. Check whether the middle of sash and frame is blocked by paint. If it is blocked, it should be removed. First, insert the cutting edge of putty knife into the paste place and cut it with laser.

If you can, hit the blade carefully with a hammer to make it deeper.

If the window is stuck too tightly, you can open it with a small crowbar.