Hello, there's 2 methods i can think of if you can successfully log onto your ps for even a second and freeze/crash. =D
1. Copy "/spawn" and go in your ps. Then paste that into chat quickly, and it will take a few seconds to register because of the entities, but it will work with a little waiting. Then set up a repeating command block with "/ekillall all (world name)" and /setworldspawn near the command block to chunk load it. /setworldspawn is a vanilla minecraft command and does not interfere with /setspawn from essentials. =D Then go ahead and knock out the falling block cmdblock
2. The second method is similar, get away from the falling sand command block, then go into /control > settings > command block enable/disable > disable command blocks > restart > remove falling sand command block > enable command blocks > restart > Problem solved.
Although if you can't even get in the ps sorry, but you have no hope. =/ Hope this helped out and you can get in at least for a little. If you just crash, maybe ask an op on your server and he can do it(if the crashing for you is client side).
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