Sometimes, incorrectly posted transactions that need to be amended or removed cannot be due to being locked in a VAT Return, Comparative Year, etc. The only workaround for this would be to post amendments to cancel out the incorrectly posted transactions.
Amendment to cancel out a Sales Invoice: Post a Credit Note with the same details as the Original Sales Invoice. If it is allocated to a Receipt, then a Minus Receipt is required for the allocated amount.
Amendment to cancel out a Purchase Invoice: Post a Credit Note with the same details as the Original Purchase Invoice. If it is allocated to a Payment, then a Minus Payment is required for the allocated amount.
After the above corrections are posted, you can either re-create the correct postings or the corrections can be kept on the system, as these will cancel out the original postings.