Hi Armageddon65 – You can record with OBS and not stream at the same time. In the bottom right hand corner of your OBS will be a red circle with the work “Rec” in it. Hit that and it will start recording your gameplay to a folder on your PC. When done, hit the button and again and the it will stop recording.
You can then open that video file and edit it with any required software of your choosing, I use Filmora 9 and its pretty decent for a low cost editing software.