Dependent and Stimulus Check

My son turned 18 this year in Feb.  He had a job last year and based on the rules of the stimulus check, he should be able to receive $1200 if I don't claim him as a dependent on my 2019 tax return which I'm about to file.  He did have a job last year and I already filed his 2019 tax returns back in April (he received a refund).

So my question is this...how do I remove him as a dependent in 2017?  Do I just remove him altogether from my tax returns?  Is this a smart move?  And if I do remove him, how do we get him in line for the stimulus check?