[GNC] Removing commission split on stock transaction

[Fred Tydeman]

I am running GnuCash 5.12 on Fedora Linux 41

I am importing stock transactions from an old Quicken.
Many of those transactions have a small commission
   (due to rounding error in price).
Those transactions end up in GnuCash with 5 splits:
  stock
  cash
  commission
  trading (stock)
  trading (cash)
I try to remove the commission split by deleting
  commission
  trading (stock)
  trading (cash)
When I click on Enter, those three splits reappear.

If I change the dollar amount in the trading (cash) split,
it reverts back to the previous value when I press Enter.

What is the correct way to remove the commission split?