I would get rid of the IRS. But then I would use all those tax attorneys and accountants to go through the entire budget to find additional savings. Give each of them a few pages and they can make edits online which would then be reviewed and sent to congress for approval. Any change that gets put into law, the creator of the change gets a bonus.
I would keep a small cadre of residual IRS employees to go after those ex-employees who are delinquent on their taxes under the old rules. If need be, jail ‘em!