even more minified. forEach doesn't return anything, so you don't need the IIFE.

  javascript:document.querySelectorAll('body *').forEach(el=>['fixed','sticky'].includes(getComputedStyle(el).position)&&el.remove())

or

  javascript:document.querySelectorAll('body *').forEach(el=>/^(fixed|sticky)$/.test(getComputedStyle(el).position)&&el.remove())