The first thing to determine is whether it is a negative voucher or a debit memo.

Debit Memo:
  1. Highlight the item in Open Items. 
  2. Look at the record ID bar (the colored strip below the buttons and above the tabs).  If it says Unapplied Debit Memo, then the item is a debit memo. 
  3. If you made the debit in error, then open the item ( double-click) and select Create Voucher. 
  4. Read the paragraph that appears to decide what date you should use. 
  5. After creating the voucher go to Item Entry and post the voucher.  This will clear out the erroneous Debit Memo.
Realize that this will create journal entries in the GL that will credit a payable and debit an expense account.  If the debit was created in error, this will effectively reverse the journal entries made by the Debit Memo.

Voucher:
  1. Highlight the item in Open Items. 
  2. Look at the record ID bar (the colored strip below the buttons and above the tabs).  If it says Voucher, then the item is a negative voucher. 
  3. Open the item ( double-click) and select Create Debit Memo. 
  4. Read the paragraph that appears to decide what date you should use. 
  5. After creating the debit memo go to Item Entry and post it.  This will clear out the erroneous negative voucher.
  6. Since you probably created the negative Voucher in an attempt to create a Debit Memo, you need to decide if you now need to create a Debit Memo. 

See the FIMS Help Manual for directions on creating a debit memo if unsure of the process. It is possible that after posting the Debit Memo in the second instance or the Voucher in the first, that the item still remains in the Open Items tab, but now with a value of $0.  Run the Clear Fully Paid From Open Items tool found in File Maintenance to remove the $0 item.