Found out a nifty command which allows you to find out what VM’s have Delta / Snapshot files. Run this when SSH’d in.
find /vmfs/volumes/ -name "*delta*" -type f -print0 | xargs -0 du --human-readable --total
Or for ESXi the command below
find /vmfs/volumes/ -name "*delta*" -type f -print0 | xargs -0 du -h