In the Disposal of Fixed Asset, you need to fill in the Quantity Disposed field in the Fixed Assets form - General tab. This quantity disposed field should be equal to the quantity acquired. Click the Dispose button and a message will appear asking if you want to dispose the fixed asset. If you select 'Yes', another message will appear stating that the fixed asset was disposed successfully. Also, on that same message, the General Journal ID for the disposal transaction will be shown. Once you click on 'OK' button, the Disposal GJ field will automatically be filled in with the General Journal ID of that disposal transaction.
Transactions for the disposal of fixed assets can also be viewed in Fixed Asset Journal under Accounting topic. The final step is to Post this transaction to update your General Ledger. See also Batch Posting.