How to unmerge NIFTI (nii.gz) files?

Hello everyone,

I’m currently working on Radiomics. To do this, I set up a directory where I stored MRI scans in one folder, and segmented tumors (labels or masks) in another. Despite segmenting and saving everything separately as individual files, I’ve noticed that all the layers were merged, as you can see in the image.

How can I separate them? In very basic terms, how do I retrieve the blue, yellow, and green layers as single and distinct NIFTI files?

Thank you!