How to disassemble pinned sprockets from a freewheel
How do you take apart the sprockets?

This is not a freeweel but rather a cassette.
By removing the pins, by drilling or angle-grinding them away. This won't cause any damage. You will have your cassette, but with loose sprockets and spacers.
However, do note the sprockets are matched to the neighboring ones in Shimano hyperglide (HG) cassettes. If you customize your cassette, then the matching doesn't work anymore and your shifting suffers. It is not a fatal deficiency, because bicycles were ridden for decades without neighbor-matched side-cut sprockets.