Can we take off the form an employer we no longer work for?

Are you asking if you can omit a W-2 income because you no longer work for the employer? No.

....well....No if you stopped working for them in 2020, because you should still get a W-2 from them.

....maybe  if you stopped working for them in 2019....i.e. Yes if they will not issue a 2020 W-2...or perhaps No,  not if you worked right up to the end of 2019...because sometimes the last week of 2019 work can end up on a 2020 W-2 form...and you would end up having to declare that as 2020 income.

I received no payment from this employer all of 2019 & 2020