This question recapitulates the debate around line-item vetoes in respect of spending bills [1][2]. Based on SCOTUS precedent, which admittedly doesn't mean much nowadays, it is unconstitutional [3].
[1] https://en.wikipedia.org/wiki/Line-item_veto_in_the_United_S...
[2] https://en.wikipedia.org/wiki/Line-item_veto
[3] https://tile.loc.gov/storage-services/service/ll/usrep/usrep...