How to render 4K footage to upload

I have a large collection of 4K footage from Australia. My problem is how to render 4K footage to upload to you? I have a Mac, and for 1080 would simply use the MPEG Streamclip to edit and mute the video. But it does not look like I can do this for 4K footage files? Would anyone have any advice to explain the best method to render the footage without purchasing Final Cut Pro etc. I don't edit, so I only need something to render 4K footage you will accept.

Thank you.

Annie

Da Vinci Resolve is free and easy to use.