I don't know how other people did but i found this (nearly by accident) for the self-destruct achievement.
subleq @IN, 0, 0
That's it!
After compiling, our memory looks like :
fd 00 00 00 00 00 ...
with a bunch of zeros after.
It will attempt to subtract address 0 (@IN aka -3) from @IN which is forbidden so nothing will happen.
Subtracting anything from @IN doesn't seem to make the compiler interpret that as valid branching, so it goes on.
Now the compiler will interpret any 3 bytes as a subleq instruction, so the next subleq instruction looks like :
subleq 0, 0, 0
That effectively resets address 0 (our @IN) to 0, and jumps to 0. Now our only non-zero byte has been removed, and we get the achievement.
An alternative i found is this, which translates to the exact same compiled memory and therefore cycles and bytes read :
.data @IN
Go play the game, and thank @Jared for it being free!