How can I crop a mp4 video and cut a part of it in Windows?

With Microsoft-only options, split the task into what Windows can do reliably and what it cannot. Clipchamp can trim, split, arrange clips and export to MP4, so use it for removing the middle section and checking the final social-media cut. True frame cropping is more limited in the built-in Windows stack; if Clipchamp's fit/fill and canvas options do not produce the crop you need, there may not be a supported native tool that performs both precise crop and cut without re-encoding. Keep the original MP4 untouched, create a copy for editing, and export a short sample first so you can judge whether the quality loss is acceptable.