TRIM at the point of killing the VM doesn't really help though - all you are doing is wiping the blocks where the data is currently stored. Your logical volume could have existed in many different physical places on those disks or on others as the host rearranges for any reason or swaps old hardware for new, so there could be "ghost" copies of your (slightly older) data all over the place, people could have had it mapped into their new volumes ages ago already.
The only way to ensure your data is secure is to use encryption to start with (preferably full-volume encryption, and make sure the keys are not stored at the providers end, so you'll need some mechanism for giving the VM the keys when it reboots and will have to trust no one can somehow read them from RAM) then you don't need to wipe the data at all: just destroy all copies of the keys and the data is rendered unreadable (to anyone given a new volume that spans physical media where your data once sat, it is indescribable from random noise).
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TRIM at the point of killing the VM doesn't really help though - all you are doing is wiping the blocks where the data is currently stored. Your logical volume could have existed in many different physical places on those disks or on others as the host rearranges for any reason or swaps old hardware for new, so there could be "ghost" copies of your (slightly older) data all over the place, people could have had it mapped into their new volumes ages ago already.
The only way to ensure your data is secure is to use encryption to start with (preferably full-volume encryption, and make sure the keys are not stored at the providers end, so you'll need some mechanism for giving the VM the keys when it reboots and will have to trust no one can somehow read them from RAM) then you don't need to wipe the data at all: just destroy all copies of the keys and the data is rendered unreadable (to anyone given a new volume that spans physical media where your data once sat, it is indescribable from random noise).