It doesn't matter if you don't have it, but it would be useful to have it, and it would save a lot of code, so I made it.
(delete|kill) entity %entity%
entity %entity% is alive
example:
Code (Text):
spawn a chicken at player
loop 10 times:
if entity last spawned entity is alive:
broadcast "Chicken is alive!!!!"
wait 1 seconds
if entity last spawned entity is alive:
delete entity last spawned entity