Reverse Expenses for a Transaction Source which does not allow Reversal

Dear Experts,

We have a custom program which puts HRMS Salary Expenses into Oracle Project Interface.

These expenses are then imported to Oracle Projects.

However, by mistake, Payroll was run for a wrong date and all wrong salary expenses have been imported to Oracle.

The Transaction Source does now allow for Ajustments or Reversals.

Even when I try to change at the setup level, it gives me error that "Update or Delete not allowed. Transactions with this source have already been imported into PA".

We need to either delete or reverse these expenses.

Most of them are already cost distributed. There are around 4000 rows of data.