Sorry for the long post. I am fortunate enough to have a facility near me to do O-lifts but I still have to go to World's once a week and this is what I have found over the years of primarily doing O-lifts. There is not supposed to be a negative on any O-lift. Wherever the lift stops is where you drop it. At the top of the snatch above your head, let it go. When you catch the clean and don't jerk it, let it go. If you are going to jerk it, then let it go at the top.
Don't ever lower anything down period. If you don't have any place to drop the weight then you have to go light and practice the safest and most energy sufficient way to lower the bar. In a snatch, when you finish, your hands are very wide.
You have three ways to lower it. 1) drop it. 2) let it go while holding on to it and let it crash into your thighs. 3) Or do the negative portion of a cuban press or muscle snatch (ouch) my shoulders hurt just thinking about it. I know a lot of us do the cuban press or muscle snatch but I doubt many of us can muscle snatch what we can actually snatch.
Lowering the clean 1) drop it. 2) release it while holding it and let it crach into your thighs. There is no other way. I wouldn't say don't do O-lifts at a commercial gym, but I would not try and lift any substantial amount of weight if you cannot drop it. If you have ever watched a meet, once the bar is over their head whether it is the snatch or C+J they let it go, they never lower it. When they workout they may not drop every single rep but they drop most.
If I have to do O-lifts at a commercial gym which I do on Sat's. I jerk from the rack or do a lot of drop jerks both in front and behind the neck. I go light and work on speed and technique. Those days I tend to do a lot of d-bell work. D-bell snatch, d-bell clean and jerk. You can release the d-bells much easier and they don't have to crash into your thighs and you don't have to drop them.
After a d-bell snatch you can do the negative portion of the side press, so you can use more of your body to lower it. On the C+J you can do a negative of a d-bell press and release the d-bells off to the side of your thighs. My workouts are based around O-lifts and I do at least some variation of the snatch and C+J every workout. This is what I have found to be the best ways without hurting yourself. Hope this helps