Very few puzzles will require block cannibalization, but it can be done, as follows: 

Remove a block: 
 #X###
 
 # ###
 
Move the visible portion: 
 ####
   <---
 
Missing block respawns and overwrites the block occupied: 
 #+##
 
 ####
 
Few puzzles may also require the player to delete-at-spawn blocks, as blocks respawn incrementally from 
the middle first. In this case the plus sign is used to represent a half-spawned block. 
Remove the middle block: 
 #X#
 
 XXX
 
Wait for blocks to spawn: 
 +#+
 
Delete the fully-spawned block: 
 #X#
 
 # #
 
While a more complicated means of separation, since all the blocks disappear, this is your only option
to enable block separation when forced to delete all the blocks in a puzzle, most likely due to a glass
covering. Blocks that respawn can also be moved out of the way; do not forget this when encountering 
block obstacles. Blocks in glass cannot be selected, but blocks in glass can be selected for movement
when a block outside of glass is selected first.