Can employer revoke I140?


I’m on H1 visa and I140 is approved from my current company. I plan to change my company based on current company’s I140. Will the employer be able to cancel or revoke it? Will I be able to keep priority dates? Do I need to have a separate conversation with employer asking not to revoke it? I’m afraid the employer will demand money for GC processing/legal costs he has incurred so far.