You can buy Crucial RAM with or without heatsink. Also RAM from any of the other major RAM manufacturers is available without heatsinks. I mean the actual manufacturers of RAM. That would be Samsung, SK Hynix, Micron (Crucial), Kingston and Toshiba (now part of Bain-Apple Group). Some are easier to find on eBay. As many are generally sold directly to computer manufacturers and aftermarket upgrade brands.
Also the heatsinks are usually decorative. Unless the aftermarket memory is overclocked and overclocked enough to need a heatsink. It is just there for looks. Sometimes they act more like an insulator.
There are plenty of videos on how to remove a heat spreader. Frankly I wouldn't do it. You void the warranty. If you don't want...