Navigate to Tools > Fixed Assets.
Note down the type, cost and accumulated depreciation, of the asset you want to remove. Then click on the Archive icon next to it, this will cease any further depreciation entries.
Do not Delete it as this will reverse all the depreciation entries.
Navigate to Settings > Accounting > Account codes.
Click on the Create account code button.
Create a new code called Profit/Loss on disposal of fixed assets. Make sure that the account type is Depreciation. Click on the Save new account button at the bottom.
Navigate to Tools > Journals > All journals.
Create a journal with the following entries:
Dr the appropriate accumulated depreciation account with the depreciation on the asset, Cr the relevant fixed asset cost account with the cost of the asset and Dr the difference to the new Profit/Loss on disposal of fixed assets account.
Hit the Post journal button to complete.
The above journal will remove the asset and its depreciation from the Fixed Asset account codes and put its net book value to the profit and loss account.
Any money received for the asset should be explained to the same Profit/Loss on disposal of fixed assets account, recording the final book loss or profit on its sale.