Your 485 has been pending for more than 180 days so you are protected by
AC21.As long as you can find a same or similar job in time, simply
withdrawing the approved 140 has no impact on your GC.
The only thing they can do to really hurt your GC is to claim (and prove)
the whole GC process is a fraud, which I highly doubt they will.
So relax and focus on finding next same or similar job asap.
btw your current job title is irreverent, what matters is the job title your
new employer is going to state in the EVL.