No, you cannot omit the 1095A from the tax return, it will reject.

Marketplace insurance requires the person to give them an estimate of their income for that year, so that they can figure the advanced premium tax credit (discount on their insurance premiums), if their income ends up being more than they told the marketplace, they have to pay back that premium (discount).

Did you LOOK at the pages of the return to see WHY they suddenly owe more money once the 1095A was added?  As a tax pro you HAVE TO be able to dissect the return and understand where and why the numbers end up where they do.

To reduce the payback, they need to lower their income, one way to reduce that payback would be making an IRA contribution (if they qualify) but for many people that's putting even more money out of pocket that they don't have.