There's a fair few. My favorites are pentobarbital for cleanliness and comfort, LSD + Height + Opiates/Disassociates for relative accessibility. LSD to eliminate inhibitions regarding self preservation and heights, Opiates/Disassociates to eliminate pain and awareness in the event that impact does not cause immediate death. The first one is legally used in some countries and progressive states, the second one not so much. The second can be sourced fairly easily, the first I'm not quite sure on yet, but there are good resources to look into.

Of course there are the obvious, gunshot to the head, however this has a surprisingly high fail rate, and bad news if you fail. In some countries access can also be extremely difficult.

There's also something to be said for a simple opiate overdose, but I'm unclear how well that would go over with someone who is inexperienced with them; high chance of throwing up and ending up in the hospital with a really bad headache. Perhaps when combined with antiemetics.

Whatever the case, any of the above options are better than having your own bone eat you alive. It does require a bit of determination, some people find it more convenient to suffer at the hands of a "medical professional" with regrettable results.